Welcome to the sixth lecture of cryogenic engineering for NPTEL program. The title of this is continuing from the earlier lecture which is properties of materials at low temperature. Here, we are considering various properties that are mechanical properties, thermal properties, electrical properties and magnetic properties. We have talked about this in the last lecture out of which the mechanical and the thermal properties are basically meant for mechanical engineers and this is what the course is meant for mechanical engineers. And therefore, we will talk about these properties, mechanical properties and thermal properties at low temperature in detail. At the same time, I will talk about electrical and magnetic property. I will touch upon these properties and I will not go into the details of these properties. And as far as electrical and magnetic properties are considered at low temperature, we will talk more about superconductivity. This S c is basically short form of superconductivity. So, we will talk more about mechanical and thermal in detail for mechanical engineers, while I will just give some information about these two property giving more stress on superconductivity as such. My earlier lecture introduced you different material properties. We talked about structures of metals and plastic. We talked about B C C, H C C, X C C C etcetera all those materials and their relevance to the mechanical properties. We also talked about the stress strength relationship which are very very important in order to understand mechanical behavior of a material at any temperature. We talked about in detail about the mechanical properties of metals at low temperature. At the same time, I touched upon the mechanical properties of plastics at low temperature because plastics also play an important role in cryogenics. In today's lecture, I will continue with the material properties of low temperature. I will give a small introduction as to what exactly I am going to talk about in today's lecture. Then the thermal properties. The essence of today's lecture of the main focus of today's lecture will be on thermal properties and thermal property variations at low temperature. Also, I will talk in brief about electrical and magnetic properties. Now, as far as the properties of the materials at low temperature are considered, the properties of the material change when cooled to cryogenic temperature and we have seen a small video. We showed to you how the properties of the material change at low temperature. We know that the electrical resistance of a conductor decreases as the temperature decreases. In fact, the electrical resistance decreases as the temperature decreases. So, as you go on reducing the temperature, the conductivity increases. In other word, electrical resistance decreases. At the same time, we know that if the material's temperature is increased, it expands. Similarly, in cryogenics, if the material's temperature is decreased, the material will shrink and therefore, the shrinkage of material occurs when cooled to low temperature and this is very important consideration and this is what we will see in this particular lecture. At the same time, we understand that the system is cooled on faster at low temperatures due to decrease in the specific heat. If I want to cool down the system at room temperature, the system will take some more time as compared to what it would take at lower and low temperature, essentially because there will be decrease in specific heat at low temperatures and this is an aspect which has to consider while cooling different materials at low temperature. With these small examples, we have very general examples we talked about. We know that the study of properties of material at low temperature is necessary for the proper design because every cryogenic design, every cryostat design, every cryogenic device has to understand how the materials behave at low temperature and their behavior has to taken into consideration while designing that particular device. Now, what are different material properties we are going to talk about under the thermal properties. So, under thermal properties, I will talk about essentially three properties. One is thermal expansion or contraction. In cryogenics, we will come across more contraction if we are reducing temperature while if we are increasing temperature, we will get expansion. Second property is specific heats of solids because specific heat is a very important function of temperature and this we try to understand in this particular lecture. Important thing is thermal conductivity. So, we will study these three properties and the variations of these properties at low temperature in detail. So, let us first come to thermal expansion. What is thermal expansion? Thermal expansion or contraction is nothing but reduction in the dimensions of a material occurring when cooled to low temperature. Simple, we know this that if we heat the material, its dimension increases. Similarly, if the material is subjected to very very low temperature, its shrinks and that has to be considered in the design of a cryostat or a cryogenic device. Now, I just show a small schematic or a small animation here where we have got a material A and material B and these two materials are joined together by a brazing or a welding or whatever process of joining we use over here and this joining naturally is then at 300 Kelvin I mean at room temperature. 300 Kelvin is always treated as room temperature. Now, this joint when subjected to low temperature will look like this. Now, why does it look like this? It shows that material A has shrunk also material B has shrunk and you can also understand that the joint which was perfect at room temperature. Now, that joint is not perfect here and the joint will start leaking and why does it leak? It leaked because both the material shrunk and the joint therefore, gave way to whatever cryogen or whatever gas flowing beneath this. That means at 300 Kelvin the joint was perfect at 80 k the joint has become imperfect the joint has started leaking. Now, this is a very important thing. This is where cryogen is comes into picture. This is where thermal engineer comes into picture. This is the contraction of A and this is the contraction of B. Now, any designer who knows this will have to consider the shrinkage of material A and shrinkage of material B before he starts joining mechanism and this requires some of the calculations to be done. Some properties of material have to be known the shrinkage is a function of temperature. So, one should know how much shrinkage it comes across? How much material A shrinks or how much material B shrinks? Does material shrink more than A or more than B? That you have to understand and those things have to be taken into consideration while designing a cryostat or any machine. So, let us see what is that parameter which defines the shrinkage. The shrinkage is now defined by the linear coefficient of thermal expansion when we are talking about one dimension or let us say length, width or height etcetera. We can define the shrinkage by lambda t and this lambda t is defined as del L by L upon delta t. What does it mean? It means that the fractional change in length that means if L is a length then del L is a contraction or expansion per unit change in temperature while the stress is constant. So, what is del L by L for a given material per unit change in temperature or per degree centigrade or per Kelvin? That is a very inherent property or a characteristic property of any material. So, lambda t is a specific property of a material and it depends on what is lambda t at a particular temperature because lambda t at room temperature could be different that means the fractional change in length per unit change in temperature could be different at 300 Kelvin at room temperature, it could be different at 150 Kelvin, it could be different at 80 Kelvin. So, this behavior, this variation of lambda t or what is lambda t at room temperature, what is lambda t as 200 Kelvin temperature have to be known before we go for further design of any joint. So, this is a very important thing because some additional stresses can get generated because of contraction and expansion of the joints. The unit of lambda t from this definition is per Kelvin which is k inverse or 1 by k whatever way you want to write it could be written sometimes it is written as even per Kelvin per k. Similarly, now this was linear coefficient of thermal expansion. Similarly, we can have volumetric coefficient of thermal expansion beta and is a fractional change in volume per unit change in temperature while the pressure is constant. So, you can have one in length, breadth and height which will give a volumetric change in thermal expansion. Volumetric change occurring in all the three dimensions and for isotropic materials where lambda t in all the three directions is same, we can have beta is equal to 3 lambda t that is understandable. Now, this variation, this particular graph gives the variation of lambda t with respect to temperature. So, we can understand now that lambda t is basically decreasing trend for every curve. This curves are meant for different materials. This is for aluminum, stainless steel, nickel, carbon steel and titanium as shown over here. And what you can see from here that lambda t is basically decreasing with the decrease of temperature. So, one thing is sure that the variation of lambda t for the few commonly used material in all the materials, we see that the coefficient of thermal expansion is decreasing with the decrease in temperature. So, this has to be understood. Also, what you can see is at 300 Kelvin, lambda t's values are much higher as compared to let us say 80 Kelvin temperature. That means, at room temperature the shrinkages are much higher, delta L by L per degrees centigrade are much higher as compared to very low temperature. This aspect also has to be considered while designing the machine. So, you can see below 80 Kelvin the lambda t value is just 10, 8 or 4 while at 300 it is of the order of 24, 25 etcetera. So, most of the contraction we can see that it happens from 300 to 80 Kelvin while below 80 Kelvin the contractions are that way negligible. Now, why does this contraction happen? In order to understand that we can understand that we can see from this figure that the molecular internal energy variations versus the intermolecular distance which is given over here. This figure gives the variation of molecular internal energy versus intermolecular distance which is given by R. What you can see here is at 0 point that is at temperature equal to 0, R 0 has got particular value. What you can see from here this particular curve shows that as the temperature increases this is the oscillation of the atoms in a particular lattice and this oscillation amplitude has increased. As the temperature increases this oscillation amplitude increases and you can see here as the temperature increases further this oscillation amplitude has further increased. Also what you can see from here that the equilibrium spacing curve which basically denotes the intermolecular distance the curve is tilting towards right which shows that this is not a very symmetric curve. This what we see from here the equilibrium spacing basically depicts the mean position of the atoms about which it oscillates. With the rise in temperature the increased thermal agitation leads to increased intermolecular distance which is what we just saw and the energy curve is asymmetric about the point R 0 stating that the atomic vibration is asymmetric. So, we can understand that as the temperature increased the curve is leading towards right. It means that they are not symmetric while when the temperature increases from T 1 to T 2 the oscillation increased while if it goes from T 2 to some additional T 3 value the oscillation will further increase and that increase will be much more than the ratio of this temperature T 3 to T 2 or T 2 to T 1. As soon as you understand this we can understand that the lambda value are changing and the lambda values are more at higher temperature than at low temperature. This is what the conclusion could be drawn from this the rate of increase of intermolecular distance increases with the increase in temperature. So, as you increase from T 1 to T 2 or from T 2 to T 3 smallest increase at T 2 to T 3 can lead to much more increase in the intermolecular distance which basically means that the lambda value is much more here as compared to what it is over here and this basically offers the explanation for the curve which we earlier saw that lambda values at 300 Kelvin are much higher as compared to what they are at let us say 80 Kelvin or 50 Kelvin. Hence, the coefficient of thermal expansion lambda t increases with the increasing temperature and this is basically the reason why material expands when heated and why do they contract when they are cooled. There is one more parameter which has to be understood called mean linear thermal expansion which is delta L by L 0. Now, this parameter also gives you understanding as to what exactly happens when the temperature changes happen from let us say from 0 Kelvin to a particular temperature T. So, if I define mean linear thermal expansion as del L by L 0 which is L t minus L 0 divided by L 0 that means length at any temperature T minus L 0 that is the length at 0 Kelvin divided by L 0. So, this curve basically derived from the values of lambda t for different materials. So, you can see from here that aluminum has got more delta L by L as compared to copper as compared to stainless steel as compared to nickel. So, here we can understand that let us say for temperature equal to 280 Kelvin delta L by L at 280 Kelvin will be around 375 that means if we change the temperature from 0 Kelvin to 280 Kelvin the length increases around 375 or delta L by L into L 0 into 10 to the power 5 is equal to 375 which means around 3.75 millimeter if we have got a 1 meter length at 0 Kelvin. So, this curve gives you the change in length for a given change of temperature from 0 Kelvin alright. Again from this curve you can see that below 80 Kelvin the delta L by L value are much smaller as compared to what they are at higher and higher temperatures. The slope of the curve is very high up to 80 Kelvin and thereafter it flattens. The mean linear thermal expansion can also be evaluated between two different temperature. Earlier we saw that mean linear thermal expansion was with respect to 0 Kelvin, but now if I have got two temperature into consideration like L T 1 and L T 2 are the lengths of the temperature at T 1 and T 2 respectively then the change in length if we change the temperature from 280 to 80 Kelvin or 80 to 280 Kelvin whatever then we can compute those two temperatures by this formula. So, in this case now delta L by L 0 will be L T 1 minus L T 2 upon L 0. So, if I get the value of L T 1 by L 0 which is let us say this and L T 2 by L 0 which is value this and if I get the difference between these two values then what I get is the delta L value if I change the temperature from T 1 to T 2. Now, this is a very important calculation which one has to do if one uses liquid nitrogen at 77 Kelvin from room temperature how much that particular part will shrink can be computed over here and this is very important to understand what will be the stresses generated how the joint will behave at lower and lower temperature this is very important and with this formula one can calculate the delta L value between two temperature changes. So, here you can see that for different materials we have calculated the temperature of the stainless steel rod decrease from 280 Kelvin to 80 Kelvin we find from here this is stainless steel over here that d L equal to 2.5 non millimeter if L equal to 1 meter at 0 Kelvin and from 80 Kelvin to 20 Kelvin d L is only 0.13 millimeter telling you that this indicates to you that maximum shrinkage again has occurred up to 80 Kelvin while below 80 Kelvin it is only 0.13. One can compare this with the value of lambda T which we earlier saw from here you can understand that for aluminum the shrinkage is much higher which is clear from this particular portion that values for aluminum are much higher then comes stainless steel then comes nickel and then comes carbon steel. So, basically the shrinkages go in order of the lambda T values and if one wants to compute the exact shrinkage one can compute by this formulae and these are very very important in order to understand how much shrinkage would occur and therefore what kind of jointing mechanism you should device or how much stresses will get generated if this particular rod is subjected to low temperature. With this now I will switch to the next property which is specific heat of solids what is specific heat this is also a very important property it is the energy required to change the temperature of a unit mass of substance by 1 degree centigrade holding the volume or pressure as constant. So, basically how much amount of energy is required to change let us say 1 kg substance by 1 degree centigrade which talks about its C p value or C v value by thermodynamics you know that C v is nothing but d u by d t that means the change of internal energy per degree centigrade temperature. Similarly, the C p value or the specific heat at constant pressure is nothing but variation of enthalpy T h by d t change of enthalpy per degree temperature change. Now, in order to understand how to calculate C v and C p or how the C v and C p change at low temperature I am going to consider only solids over here because that is the material normally we come across in calculations. Now, lot of things evolved from right earlier from 1911 and in 1911 Dolong and Pettit observed that the heat capacity of the solid are independent of temperature. See that time the low temperature availability was not so much and Dolong and Pettit came to the conclusion that the C p values or the C v values for solids are independent of temperature why because each lattice point absorbs same energy as every other lattice point. So, that means all the lattice point behave in the same way they absorb the same amount of energy and therefore, there is no dependence of amount of energy absorbed over temperature and by equipartition of energy they calculated that u is equal to 3 r t and therefore, d u by d t is equal to 3 r which is C v is equal to 3 r and therefore, they found that d u by d t is nothing but a constant figure. So, whatever happens even if the temperature decreases or increases C v is equal to 3 r value this is what we observed by Dolong Pettit's rule. The next observation which went to Einstein where the quantization came into picture and Einstein treated the solid as a system of simple harmonic oscillators. Now, you know that all the atoms in the molecule oscillate what Einstein observed was that all these oscillations are of the same frequency. So, all the lattice movement that is happening in the lattice all the atoms there which are vibrating they are all vibrating at the same frequency which is not a very realistic observation then, but again it was one of the evaluation that happened over Dolong Pettit's observation. However, the next scientist who came into picture was Debye. Now, Debye treated the solid as an infinite elastic continuum and considered all the possible standing in the material because there are lots of different vibrations that are coming into picture. What are different frequencies coming into picture different oscillating frequencies all the molecules are not oscillating really at the same frequency but, they have got different frequencies. And what Debye concluded is a parabolic frequency distribution exists he derived a parabolic frequency distribution was derived for the atoms vibrating in lattice and he considered all this frequency distribution in order to calculate C p and C v. So, he presented a model to compute lattice hit capacity per mole which accounts for all the vibration frequency for all the lattice points and this is very important thing because this comes very close to the realistic picture of a lattice. So, what he did was the Debye model gives the following expression with lot of calculation he came out with the expression which gives lattice hit capacity per mole and expression is like this 9 R T upon theta d and theta d is nothing but, characteristic Debye temperature and then this expression takes care of the all the lattice vibration frequencies all the oscillating frequencies in the lattice. And he again simplified this by having this expression as d of T by theta d which is called as Debye function. So, this is the most important thing that whatever complicated part was there in order to consider all the parabolic frequency distribution he indicated or he calculated that as a Debye function and one can get the value of Debye function. And therefore, if we know the Debye function at a particular temperature we can compute the C v at those temperatures right. In this particular expression x is a dimensionless variable and this x basically nothing but, h view upon k T which is a Planck's constant into frequency Boltzmann's constant k and temperature. So, from here you can understand that x considered all the frequencies of vibration. In this equation in the equation which is over here the only value of theta d is going to change and what is this theta d is basically nothing but, Debye characteristic temperature. So, for different materials now it will have a characteristic Debye temperature and if I know this Debye temperature I can compute the value of C v provided I know the Debye function values all right. So, the whole thing become very simple one can compute the effect of temperature variation on the values of C v. From this expression we can understand that at very high temperature that means, T greater than 2 times theta d the specific it obtained from the above equation approaches to 3 r values and this is nothing but, what we got earlier by Dolong Pettit's value. So, at higher temperatures at very high temperatures at room temperatures and above what we will have is the C v is equal to constant values which is equal to 3 r and at low temperatures where T is less than theta d by 12 this will come into a very low temperature category. The Debye function here in this case approaches a constant value and at d 0 what we have is a 4 pi to the power 4 by 5 is constant value. If I put the Debye value over here particular C v value will be function of only temperature now in this case while all other things are constant. You can see here now at lower temperature the C v variation is T cube directly perpendicular to T cube all right and this is a very important conclusion Debye came up with that the variation of a cubic equation in absolute temperature at very low temperature C v is directly proportional to absolute temperature to the power 3. So, at lower and lower temperature you can imagine this behavior of C v will be and this is the curve which basically gives the value of C v by r with T by theta d. So, if I know the T and if I know theta d theta d is a characteristic temperature for any material. So, what you can see is for higher temperatures where T is more than 2 times theta d or 3 times theta d the C v by r is almost constant which is actually equal to 3 times r while at lower and lower temperatures what you see is C v by r is coming down with the power of 3 as a temperature coming down and therefore, you can see the steep decrease at a lower temperature side and this is a very important curve in order to calculate the value of C v. So, in general what you can see from here is that the specific heat decreases with the decrease in temperature all right which is obvious from this particular figure. Now, this table gives you different values of the theta d for different materials. So, you got a aluminum 390, you got a beryllium, you got a calcium copper etcetera. If I know the theta d values for different temperature for different materials then I can calculate T by theta d and then I can go back to this curve I can compute the T by theta d and calculate C v of that particular material it is as simple as that. So, if I know theta d I can compute T by theta d and then I can correspondingly compute the value of C v in that case. So, if I want to calculate the value of C v what I am saying I am repeating the same thing the calculation of C v for a particular material at a particular temperature T inverse following procedure refer to the table and find out the value of theta d calculate T by theta d and interpolate the value on the graph to obtain C v by R. C v by R is known just multiply C v by R by R value where R is the specific gas constant and then what you get is the value of C v. If the value of T by theta d is less than 1 by 12 then we know that we have got one more expression which has been given earlier we can use that correlation we use the value of T by theta d and compute the value of C v directly in that case all right. So, this is how we can calculate the value of specific heat at lower and lower temperature if one knows the value of theta d for that particular material. The next property which I am going to talk about now is the very important property again thermal conductivity in solids. Now, why do we require the knowledge of thermal conductivity in solids at low temperature is because of some examples I am trying to give you. So, in a cryostat the solid members could be metal or non metal could be stainless steel could be copper could be plastic nylon etcetera and this material conduct heat from high temperature to low temperature. Sometimes we have got some suspension member in order to support a cryostat which will definitely take heat from room temperature and take it to the low temperature. So, for these members the thermal conductivity K T should be as low as possible otherwise they carry lot of heat from room temperature to the cold temperature and therefore, the cryogen there will be more loss of cryogen or some additional cooling effect has to be used for this and therefore, we have to see that the conductivity of this particular material is very very low we have to see that thing. On the other hand I will give the other extreme example wherein you want to now transferred cold because you want to cool something because lot of cold has been generated in a system let us say in a cryocooler and we want to cool a sample or we want to cool a gas and therefore, we want to have a material which has got very high conductivity at low temperature and in this case I would like to achieve base heat transfer of the cold generated and therefore, copper can be used as a medium due to its high thermal conductivity. So, I have to select a material in such a way that where I want minimum losses to be coming on a system then I should use low thermal conductivity material like nylon like stainless steel, but wherever I want that the heat transfer should be as high as possible therefore, I should use the material which has got high thermal conductivity like copper like aluminum etc. The thermal conductivity in solid let us say KT is a property of a material which indicates its ability to conduct heat. Now, this particular curve this particular graph shows the thermal conductivity variations at lower and lower temperature. You can see two types of curve one is a curve which is going up and then coming down which is for pure material or pure copper in this case. Well you can see other materials like aluminum, carbon steel, stainless steel we show that as the temperature is coming down the temperature below let us say 200 Kelvin is coming down continuously like this. So, these are basically alloys or impure material we can call them well this is the pure material, but in general you can understand for these materials KT decreases with the decrease in temperature. However, as I just indicated to you earlier for pure materials the variation is slightly different or one can say even quite different from as compared to the impure materials or alloys. So, this is very important to understand what exactly happens over here, what exactly happens over here and I will just try to give you some explanation for these two different curves. For pure materials the for any material for that matter the electron and phonon motion cause heat conduction right. Basically thermal conductivity is because of the motion of electrons and phonon. Phonon is basically the lattice vibration and these two contribute to the heat conduction. Now, the contribution of the electron motion to heat conduction is predominant above liquid nitrogen temperature. As you know that liquid nitrogen temperature is a dividing line in cryogenics and above liquid nitrogen temperature or let us say 77 to 80 Kelvin above this the electron motion of heat conduction is predominant as compared to phonon motion alright. So, at temperatures below l n 2 below liquid nitrogen temperature phonon motion is dominant. So, you got a two variations above liquid nitrogen temperature what you have is a electron motion contribution is more while below it is not electron motion but phonon motion is predominant at lower temperature and this is basically what makes the difference in the behavior as you see in pure material. Now, the thermal conduction depends on the product of in electronic specific heat and mean free path. So, if I say q which is a conduction is basically directly proportional to two parameters that is electronic specific heat and mean free path. Now, this product is constant above l n 2 alright. So, what is happening above l n 2 is as you come down the temperature up to let us say 80 Kelvin from room temperature the electron specific heat is decreasing while the mean free path is increasing. The electron mean free path is increasing and therefore, somehow the product of this specific heat electronic specific heat and mean free path is remaining constant above liquid nitrogen temperature which makes that the thermal conductivity k t is remaining constant above liquid nitrogen temperature right. What is happening below as I said below the liquid nitrogen temperature it is not the electronic specific heat which is predominant but the phonon specific heat is predominant. So, as the temperature is lowered the phonon contribution increases and the k t is varying as 1 by t square. So, you can see that if the temperature is decreasing the phonon contribution is increasing in this case which was not. So, as far as the electronic contribution was considered also as we know earlier that as the temperature is coming down the mean free path is increasing alright. So, here what you see now at below l n 2 temperature the phonon contribution mean free path also increasing the value of k t. So, at lower temperature from let us say below l n 2 the phonon contribution increase plus the mean free path also has increased which leads to increase in thermal conductivity for pure material. What this will happen only up to a particular temperature what happens at this temperature? At this temperature the thermal conductivity reaches a very high value until the mean free path of the electrons equal to the dimensions of the test specimen. So, naturally the mean free path has got some limitation and it increases to a maximum to a value which is equal to the maximum dimension of the test specimen alright. So, beyond which now it cannot increase that means it has reached a constant value and therefore, below this temperature now below this temperature the conductivity starts coming down at this point or it reaches a maximum over here and because it has reached a maximum value when this condition is reach that it has reached the maximum value the surface of the material exhibits a resistance to the motion of electrons alright. So, basically the resistance is offered by this material to the flow of electrons and flow of phonons and therefore, it causes the value of k t to come down below low temperature below 10 Kelvin region etcetera. So, this explains why you got a constant kind of a curve up to let us say 80 Kelvin and below 80 Kelvin it goes very high up to this point because of the phonon contribution and because of the electronic mean free path increase and then it starts coming down because now electron mean path has reached to a maximum value and the surface has started offering resistance to the flow of electrons. This is a very funny behavior this is a very typical behavior as far as the pure materials are considered. As far as the impure and alloy metals are considered we can say that the electron and phonon motion in this case are of same magnitude. So, the contribution which is coming from electron and phonon both is almost of the same magnitude in impure and alloy metals alright. So, below a particular temperature phonon is predominant above a particular temperature electron is from predominant that aspect is not existing in this case both of them contribute equally as far as the impure materials or the alloy materials are considered. What happens for the decrease in the thermal conductivity in these materials then the impure metals have got imperfection and that is why they are called as impure materials and they have got imperfections like grain boundaries and dislocation you know about this we have talked about this in the earlier lecture. So, you have got imperfections like grain boundaries and dislocations and this basically are kind of hindrances to the motion of electrons right. What happens the electrons strike these imperfection and they get scattered alright. So, an additional scattering of electrons occur due to grain boundaries and dislocations. Now, this scattering is proportional to T cube for grain boundaries and T square for dislocation alright at very low temperature what it means is as the temperature comes down the scattering become less and less and the less is T cube proportional and T square proportional if we talk about a particular dislocation of grain boundary or dislocation respectively which means that we are getting an additional advantage of scattering because of which electrons were conducting heat from one point to another, but this is not happening at low temperature because the scattering has reduced drastically at low temperature. So, at low temperatures scattering decreases as a result K T decreases with the decreasing temperature in impure metals and alloys. I am sure it is clear to you that in this particular cases the scattering phenomena decreases at low temperature and therefore, the thermal conductivity in this case decreases at low temperature. These materials do not exhibit any high maxima like that of pure metal. So, what we saw in a pure material we do not see in this particular case thermal conductivity integrals this important parameter which has to be understood while calculating the thermal conductivity loss at low temperature. As we found that the thermal conductivity K T is a strong function of temperature the term K T dT is very important. So, we have just seen that the K thermal conductivity is a strong function of temperature. Due to this variation in K T the calculation of heat transfer Q can be very complicated. If I want to calculate the conduction loss between 300 Kelvin to 80 Kelvin I have to consider the K variation with temperature and then calculate for each temperature in order to know how much what is the loss of conductivity between these two temperatures. And therefore, a simple method is proposed in order to simplify the calculation of Q. This method uses integral K dT as a parameter is called as thermal conductivity integral which basically sums up the effect of variation of K T with respect to temperature change alright. So, K T dT is a parameter which is directly offered for a particular material and therefore, one can get the what is the K dT parameter in a particular given temperature interval and this benefits a lot by calculating the loss due to thermal conduction. How we can see now? The Fourier's law of heat conduction is given by the following mathematical expression which you know Q is equal to minus K into A into dT by dx alright. Now, this we can club as K T and dT can be clubbed together while A x upon dx can be clubbed together and if we do that thing what we get is this. So, Q is equal to now here minus A x upon dx into K T by dT. In this method Q is expressed as below now I am just representing this Q in this simple format minus G into theta 2 by theta 1. Now, this G is nothing but this parameter A x upon dx which almost remains constant for a regular physical material and K T dT is nothing but theta 2 minus theta 1 that is temperature let us say T 2 and T 1 it talks about these two parameters alright. So, A x and d x is basically represented by G while K T dT is given by theta 2 minus theta 1 where theta 1 and theta 2 are expressed as thermal conductivity integrals. So, theta 2 is a thermal conductivity integral at temperature T 2 while theta 1 is a thermal conductivity integral at T 1. So, K dT now is taken as integrals called thermal conductivity integrals evaluated with respect to datum temperature. So, we found that theta 1 is nothing but what is the K T dT from T d or any datum temperature to temperature of my interest let us say T 1 and similarly theta 2 will be from T d to T 2. The datum line should be same in both the cases and this datum line various books gives various datum lines could be 0 Kelvin or 4.2 Kelvin alright. So, if A c s that is area of cross and is constant G is defined as A c s by L which is what we saw and from this now what we see is a curve which gives variation of K dT versus temperature. So, if I talk about 100 Kelvin I have got K dT value for a particular material as this which means that from 0 Kelvin to 100 Kelvin I have got K dT value up to this point and let us say at 10 Kelvin I have got K dT value as this and if I take a difference of this two I can calculate the loss of conduction how much loss we have because of the thermal conductivity from 100 Kelvin to 10 Kelvin. In the calculations the actual temperature distribution is not required but what you require is only the end point temperature I do not have to worry what happens from 100 to 10 Kelvin I do not have to worry about 90, 95, 85 exactly like I just know the value of K dT at 100 Kelvin I need to know the value of 10 Kelvin if I know these two values I can straight away calculate the amount of Q that will be loss because of the thermal conduction. So, here this technique is widely used in the analysis of heat leaks if the day term temperature is taken at 0 Kelvin and the two ends of a specimen are maintained at 100 Kelvin and 10 Kelvin respectively then the K dT integrals are given by if I want to calculate now amount of loss is occurring because of temperature change from 100 Kelvin to 2 Kelvin for a particular material if I am talking about aluminum, phosphodon or stainless steel whatever then what I am going to do is find a value of K dT for a particular material it is a phosphor bronze at 100 Kelvin which could be around this minus at value of K dT at 10 Kelvin and the difference between the two is nothing but the heat loss due to conduction in a temperature region of 100 to 10 Kelvin temperature what I need to know only one value here one value here and the difference between the two will give me K dT multiplied by G is basically going to give me the amount of heat lost because of thermal conduction with these three properties what we just talked about is thermal expansion we talk about the specific heat capacity we talked about the thermal conductivity with these three thermal properties I will come to now electric and magnetic property I will touch in very brief in this case the electrical conductivity as you know it is defined as the electric current per unit cross section area divided by voltage gradient in the direction of the current flow. So, we know that V upon I is nothing but resistance I am talking about the reciprocal of that that is electric current per unit cross area divided by voltage gradient in the direction of the current flow this is what electrical conductivity is given as the electrical resistivity is opposed to that alright. So, electrical resistivity is it is reciprocal of electrical conductivity as you know that decreasing the temperature decreases the vibration energy of the ions as you know that as the temperature decreases the energy decreases and therefore the vibration energy of the ions also decreases this result in smaller interference electron motion these ions these are positive charge actually ions which are basically are the resistance that is offered to the motion of electron motion electron motion creates a current. So, at lower and lower temperature the resistance offered by these ions is less and less and therefore the electrical resistivity in this case decreases. Therefore, electrical conductive the metallical conductor increases at low temperature and it is a very simple physical explanation to understand why at low temperature electrical conductivity of the metallic conductor increases at low temperature. Now, this particular curve gives the electrical resistivity ratio with temperature for different materials like aluminum, iron and copper and what you define electrical resistivity ratio as is defined over here the E r r is defined as r T upon r 273 that means r T is at any temperature T and r 273 is nothing but 273 Kelvin at that is 0 degree centigrade. So, you can understand that r T by r 273 is equal to 1 for all the materials and it is this point the variation of electrical resistivity ratio for some commonly used material is as shown over here and what you can see now r T upon r 273 decreases for all the materials over here. However, the decreases are different with different temperatures with different materials. So, what you can see for copper r T at any temperature let us say at 100 Kelvin r T upon r 273 for copper is much smaller as compared to what it is for aluminum. What does it mean that r T at 100 Kelvin r 100 is much smaller value as compared to r 100 for aluminum which means conductivity of copper at 100 Kelvin is much higher as compared to what it is for iron or what it is for aluminum which is what we know alright. So, this is very important to understand that how this resistivity varies at low temperature or how this ratio varies at low temperature. Also important to understand that the electrical and thermal conductivity are related by Wiedemann Frehn's expression. What does it do? Wiedemann and Frehn's expression basically finds a relationship between thermal conductivity and electrical conductivity alright. So, K T and K E are nothing but thermal conductivity and electrical conductivity. So, K T upon K E into T is equal to 1 by 3 pi K upon e to the power 2. You can see that this particular parameter is almost constant because K is a Boltzmann constant is the charge per electron and you can see that this is a completely constant value which will not change with temperature. If suppose the T comes on this side then you can understand that K T upon K E is a function of temperature only. It means that the ratio of K T upon K E is a product of a constant which is this and absolute temperature and is represented like this. So, K T upon K E is equal to A T. It means that as the temperature gets lowered if we are reducing the value of T the K T upon K E also gets reduced. It means that K T gets reduced or K E increases. The two possibilities we know that the thermal conductivity decreases at lower temperature. We also know that electrical conductivity increases at low temperature because of decrease in thermal conductivity and because of increase in K E at lower temperature K T by K E they move in such a way that at a particular temperature K T by K E remain constant or if the variation of temperature is given K T by K E will move according to this particular expression. This finishes whatever I want to talk about with regard to the electrical conductivity. Just to sum up what we have done in this particular lecture is the coefficient of thermal expansion decreases with decreasing temperature. This is what we talked about lambda T. Lambda T was nothing but equal to del L by L divided by delta T. So, what we understand from here is for different materials you have got specific lambda T value and in all those materials as the temperature decreases the lambda T value decreases which means that the material whatever it is it shrinks when temperature gets lower or it expands when the temperature increases. For pure material like copper what we saw K T remains constant above liquid nitrogen temperature. Below liquid nitrogen temperature it reaches a maxima let us say around up to 10 Kelvin and after that below this particular temperature it decreases steadily and we have understood the reasons as to why does it remain constant above liquid nitrogen temperature, why does it go from l n to temperature below up to 10 Kelvin and why does it basically later on decreases below 10 Kelvin to the value 0. Impure materials K T decreases with decrease in temperature and also we understood that the integral K D T is used to calculate q and we also saw how this K D T value is calculated from the curve. The electrical conductivity of the metallic conductor increases at low temperature this is what we understood at the same time the electrical conductivity and thermal conductivity are correlated by Wiedemann Franz law. So, here we summarize whatever we have discussed in today's lecture. Now, you must have realized that there are lot of equations, lot of curves, lot of tables wherein you should be able to calculate the specific heat at particular temperature for a particular material or the shrinkage of a particular material at particular temperature or the loss due to thermal conduction from let us say room temperature to 77 Kelvin or room temperature to 4.2 Kelvin or if the particular rod is attached between 100 Kelvin to 10 Kelvin then how much load it gives on a 10 Kelvin cold that has to be calculated that has to be understood and all these problems in the form of tutorial we will discuss in the next lecture which will be a very important lecture to understand how to calculate these losses where the mathematical relationship between these particular parameters and the tables will come into picture. At the end I have got some self assessment exercises given kindly assess yourself for this lecture very honestly they are all self assessment please go through them try to answer and at the end we have given the answers for those questions. So, that you know whether you have answered them correctly or not thank you very much.


A B-1B Lancer assigned to the 37th Expeditionary Bomber Squadron conducted a hot pit refueling during exercise King Sword 23 at Masawa Air Base Japan to support Pacific Air Forces training efforts with allies, partners, and joint forces and strategic deterrent missions to reinforce the rules-based international order in the Indo-Pacific region. King Sword 23 is the latest in a series of joint bilateral field training exercises designed to increase combat readiness and interoperability of the Japan Self-Defense Force and U.S. Forces. The first time a B-1 bomber from Ellsworth Air Force Base has been in Japan probably five years. Hot Pit Refuel essentially is a special refuel procedure that allows us to keep crew on board and two motors up while we refuel. It saves time on the ground, airframe hours, and maintenance hours as well. A hot pit refueling is useful because it allows us to essentially turn and burn those aircrafts and we get them back into fight.


What's up, everybody it is Saturday night I know that you all have been wanting to see more content like this and have been actually pretty receptive To this type of content be sure to give this video a thumbs up or making some chicken parmesan Or more so my wife is what is it the main chef the head chef? I'm the sous chef. I'm not even the sous chef I'm like the guy in a movie that is a mess It is just lucky to even have a job also. Thank you to HP for sponsoring this video They sent me over at their Bluetooth Travel mouse that they recently released and I'm gonna be talking more about that later on in a video So be sure to stick around I Want to grab some coffee I overslept significantly today and hopefully I don't regret that too much But it's already burning up in here. It's like 80 degrees outside already. I Got this new coffee book or a coffee book What got this new coffee table book called where to go win and just for like bureau shots Just to spice things up, but I also was intentional in getting like a book that I will actually read and It's got some really beautiful imagery I would like to visit at least 10 places in this book and since we're on the topic of traveling Let me take a moment to talk about HP's Bluetooth travel mouse Which is something you're definitely gonna need if you are someone who is either always on the go or is someone that likes to take your iPad tablet Laptop with you whenever you travel and you want to pack light the first thing I noticed when I started connecting the HP Bluetooth travel mouse to my computer is how easy it was to pair it through dual Connectivity and my computer automatically noticed the mouse I got some all this is and Surprisingly HP did not compromise the form of this mouse or the shape of this mouse Despite its size has like these grooves on the side actually feel really good for your thumbs to rest on the soft touch Rubber grip actually feels great when using the mouse And I think that's one of the main reasons why it feels ergonomic and comfortable in the palm of my hands despite how small the size of this mouse is one thing that HP made sure was a feature that couldn't go unnoticed with this mouse is that you can use it on any surface And it's just as responsive on a mousepad as it is on any other flat surface Which is something you'll appreciate on the go since peripherals have become increasingly smart I kind of expect a peripheral like a mouse to come with some sort of like application that allows you to customize the buttons on the mouse and luckily HP has a Accessory center dedicated to customizing the buttons on the HP Bluetooth travel mouse I'm a pretty simple guy So I'm gonna be using the peripheral buttons for desktop necks and desktop previous just to swipe Between displays it was a little weird using a double-a batteries for this mouse I'm used to like USB type-c Charging however the battery life is great Lassing you about 24 hours and having standby technology that way You know you forget to turn it off It doesn't die when you start using it again definitely a Recommendation for me if you're looking for a mouse that has a small form factor so you can pack light on the go Thank you to HP for sponsoring this video and for sending over this Bluetooth travel mouse. All right Man I Feel like there's so much I haven't told you all so many life updates So that's the whole really purpose of this video outside of just like a kind of chill weekend kind of video But I feel like I've been hiding things from you all into an extent there are a couple things that I hid from a lot of people for months and Now I can talk about everything That's new in my life. You probably know this already just from looking at the title but I started a new job and I've been working remotely for almost a month now and the company I work for is Headquartered and headquartered based is based in Jersey City Which is from what I know right across the Hudson River from New York City? So that's why in the title at least I think I'm gonna put in a title like landed a new tech role in the New York City area and It took a lot of twists and turns to get to where I'm at now and I just thank God for this opportunity But it's it's a really really interesting story And I'm actually really excited to be able to share with you all because maybe it'll inspire you to pursue Something that you're passionate about interested in along with just being transparent with How to get into a tech role, especially for a fortune, you know, 500 100 type of firm All right, the background was bothering me for a little bit. So let's start. Let's go all the way back to January. So January 6th was the day that I actually interviewed for a Technical solutions engineering role with Google. I know it's pretty random But basically a recruiter reached out to me in September Talking to me about this role That's in GTEC, which is a technology department within Google And I wasn't interested in a role really and I don't mind not coding all the time and Doing things that are a bit more high-level more business focused and more interaction with, you know stakeholders customers product team kind of like a middleman between Customers and even the engineering and product teams. So I did the interview take a long story short I pass it couldn't believe I pass it and Here's the thing. I did a lot of studying. So I had been studying for that interview since like the beginning of December I kid you not. I literally was studying on New Year's Eve like when everyone was celebrating and drinking and having a great time on New Year's Eve After I wished everybody a happy new year at my in-laws house I quickly went down to the basement opened up my iPad and started studying for this GTEC solutions engineering role. It actually was worth studying because you know passing those Interviews made me more confident in my abilities Technically now granted. I will be honest with you a solutions engineering role is like a step below a software engineering role Not maybe necessarily with pay, but it is when it comes to technical aptitude But what you have to offer as a solution engineer is because you do have good technical skill sets I still did my onsite still consisted of a technical interview when I was asked a multitude of coding and algorithms and data structures questions But you also bring that business savvy and interpersonal Soft skill sets. So you kind of like merge the two together and you have a solutions engineer fast forward to March I couldn't really find a team that matched based on my skill sets and experiences and what they were looking for and From what I've seen it seems like being in the team matching phase at Google is almost like purgatory I think I was waiting for like three to four months and My wife ends up finding this like Hiring event with the firm that I'm working for was doing for people of color I was like no, I'm not gonna do it because the location was Houston, Texas But then I was like what the heck I want to get out of the city that I'm in right now And Houston doesn't sound like a bad place to get warm weather. They have palm trees You're not that far from the ocean I apply for this event and the next thing you know recruiters start reaching out to me Asking me like what I'm interested in if I'm interested in moving to Houston and I was like Honestly, I would like to move to New York and next thing you know I get a team who is interested in me as a candidate. We do an interview I tell them that hey at any moment I can be offered a role from Google because I'm in team matching phase and they didn't waste any time with a Really nice offer and most importantly the opportunity to move to New York City Which is something that I've been trying to do for at least three years now So obviously I ended up accepting the role for the firm in the New York City area and you all can figure out Where I work. It's all my LinkedIn profile during that process. I did a lot of soul searching I thought about doing a video where I talk about turning down a role from a fan company But I almost felt like since it wasn't a sweet role. Is it really worth it? Was it legit? And I obviously was legit, right?  I'm not a sales engineer I'm not a sales person and that's kind of what that role was looking for with the blend of technical skill sets And I had to do some soul searching and say hey, what's most important to you? Is it the company? Is it the role? Right? What about the team? How Invested is the company and you so that's a pretty major life update I'm really excited But I also sometimes forget that I'm moving because I'm not moving until the fall So it still doesn't feel real yet like the job itself does and I'm actually really happy about the decision I made it's funny to go from like a big company to an Extremely big company and I can see the difference especially since this company is global And I work with team members from literally all around the world and I I appreciate that I see a huge Difference and diversity off-rip, which is something that I really appreciate and I'm glad to experience along with being able to move in a city that just has More going on and more opportunities for people like myself who are looking for creative You know Experiences and opportunities in the tech industry along with having more diversity So we haven't decided you know where we're gonna move maybe live in one of the like waterfront neighborhoods I co-boat in Jersey City. There's a couple others. That's an option. It just depends on how often I'm We would prefer to live in like Brooklyn like that would be dope Maybe Manhattan, but we really like Brooklyn, but yeah, I guess that's something that we could think about later on We've been talking about doing Airbnb's maybe like, you know an Airbnb for a month in different boroughs In different cities within Jersey City as well. Yo, I gotta show you these Kobe grinches I'm so happy. There was a sneaker event a couple weeks ago that I went with my homie Carl and I traded for some sneakers these Kobe six Grinches look at this sneaker This might be the most beautiful sneaker I've ever seen in person. I hope this video does some sort of justice but um, I Couldn't afford a sneaker like this growing up. I remember this came out in 10th grade the Kobe six grinches they came out in 10th grade and One of my team members had and I was like man that sneakers crazy, but uh, yeah It's funny how things come full circle, but uh, just wanted to show you all that I want to do more content like this where I talk about my sneakers It'd be fashion, but I want to keep you all too long once again Thank you to HP for sponsoring this video Be sure to give this video a thumbs up helps out with the algorithm a lot I put in a lot of work when it comes to these videos So it lets me know like hey, you all enjoy this content. So subscribe to the channel if you haven't already I love you all to become a part of this really cool community of Creators engineers, you know the curious the fam and as always have a blessed rest of your week I'll be praying for everyone who's been dealing with allergies and as always. I'll see you all soon. Peace


the best careers for extroverts. That's what we're going to be talking about today, but before we get into that, make sure to gently tap the like button in order to defeat the evil YouTube algorithm. On this channel we talk about personal finance, careers, degrees, and different opportunities that are going to lead you to success. We also go over some of the common traps that people fall for and how you can avoid them. If that sounds like something that interests you and you haven't done it already, go ahead and hit the subscribe button, ring the notification bell in order to see more content like this. And with that out of the way, let's jump right into it. Number 10 on the list is one that I've talked about before. It's going to be a lawyer. This is going to be someone who practices or studies law as a lawyer or a counselor. And I can already see the comments now. Clown, Shane, you clown, you said this degree was overrated and now you're putting it as one of the top 10 degrees on another video. You clown, why are you lying? Just because I think this is a career that's overrated, meaning in my opinion, the perception of the career is so far different than what the actual reality of what people and lawyers have to go through on a day-to-day basis. That's what I mean by overrated. This doesn't mean that for the right person, this can't be a decent career that can work for you. And a true subscriber, a true member of Team Hummus knows that I only post the bestest and the most correctest information possible. Anyways, BLS says lawyers make around $122,000 a year. There's 813,000 jobs out there and it's growing at 4%, which is as fast as average. Now, I did just make a video talking about how getting a law degree and becoming a lawyer is one of the most overrated careers. Pop culture glorifies being a lawyer. There's a lot of different shows out there that make it seem like it's one of the best careers ever. And it did used to be a really good career. Now, just because I think it's overrated doesn't mean that it can't be a good career for the right person. You can check out my video for more information on that, but basically someone who's extroverted, they're an A-type personality, they're willing to work 80 plus hours a week and basically never have any time off. Even when they're on vacation, they're still going to be having to do work. If their boss calls them up in the middle of vacation, literally in the middle of a bar in Las Vegas like happened to one of my friend's cousins, they still have to get that work done. It's one of those careers that's high risk and it's also a very high reward. Many people who get law degrees either end up never becoming a lawyer at all or they work as a lawyer for a very short period of time and then they decide that they don't want to have anything to do with it. Others join big firms, start at the bottom, work their way up and eventually make it to the point where they're making over 5 million dollars a year. This is what I found when I did my research for the video, careers that create the most millionaires. Lawyers showed up as the number four most common career in the top 10% of earners as well as the top 1%. So as long as you make sure you know exactly what you're getting yourself into and you're the right type of personality and you do your research, this can be a really good career. Number nine on the list is going to be salesperson. All right, so I've got a pretty strong opinion about sales jobs, okay? I really like them. They are awesome. Everybody should get a sales job at least once in their life. Even if you're the most introverted person ever, even if you end up hating the job, you will learn so much from a sales job. Now a salesperson is obviously someone who sells goods and services. A common example of one would be someone who sells cars. So an example of a job you could get is a financial service sales agent and they make around $62,000 a year. There is 464,000 jobs available and it's growing at about 4% which is average. Now as you can see, this isn't like an insane salary or anything like that. And to be honest with you, the salaries are going to vary quite a bit. Gee, I watched this channel to learn how to secure the bag, bro. Why are you showing me this low tier trash? How much you make is going to depend on so many different factors. Your experience level, your skill level, what type of salesman you are, what company you work for, what industry you're working in. Now if you went out there and you asked all the different billionaires and multimillionaires what job they all had in common in their past, they contributed to them getting to the point where they are right now, they would say a sales job. And the reason I know that is because they actually have done this. But hey, not everybody wants to become a billionaire. Most of us want to have a nice lifestyle but we don't want to have to deal with all the stuff that comes along with being like a high net worth individual. Most of us just want to live a nice lifestyle, have a nice house, enjoy a job, buy a nice car.   It will help you no matter what career you end up going into. Now if you did want to be like a pro salesman, you like you want to be a salesman for life, what I highly recommend you do is make sure to go into an industry where the commissions are higher. So make sure to go into an industry where there's a lot of opportunity for salesmen. Now you got to do your research on this, but some of the obvious ones are going to be like finance industry, selling things like insurance, for instance, you could also go into a technology industry sales job where some of the salespeople are making upwards of $5 million a year. By the way, I'm not saying that introverts can't do this one. It's just one of those jobs I've noticed where the people who do the best tend to be extroverts. That's just my opinion. Okay. That's just my opinion. Number eight on the list is going to be a physician. This is going to be a medical doctor. They're going to practice medicine at the highest level. Now BLS shows physicians making over $208,000 a year. It's actually quite a bit higher than that. It really depends on what specialty you go into. Orthopedics, for instance, makes over $500,000 a year. So this number is definitely on the lower side. Now there's a bunch of different types of doctors. You can't really lump all of them in together. But in my opinion, because of the fact that you're constantly going to be seeing new people, you're going to be meeting patients you've never met before, you're going to be communicating with all different types of healthcare professionals from nurses, pharmacists, et cetera. In my opinion, it's a good idea if you are a little bit extroverted. You have to be able to communicate at an extremely high level.  And the reason for this is because you're going to be communicating on different levels depending on who you're talking to.  Whereas if you're talking to another medical profession, you might say, oh, you've got GERD, gastroesophageal reflux disease. If you're talking to a patient about research, you would say that something is statistically significant. Whereas if you're talking to another doctor or a pharmacist, you might mention that the P value is less than 0.05. And you also might talk about whether the study has enough power. If you say these types of things to patients, they're going to look at you like you're speaking a foreign language. These are oversimplified examples, but I think you get the idea here. You're constantly going to have to be talking to tons of different types of people. All of them are going to have different skill levels. They've all got different jobs. And you are going to have to communicate in completely different ways with all of them. You're going to be meeting new people all the time. You're going to be around big groups all the time. This is one of those things that with most of the doctor professions, it would help a little bit if you're extroverted. Now, as a doctor, you're also pretty much by default kind of a manager. You're basically a leader because of the fact that all of the other healthcare professions kind of look up to you. And this is whether you want to be a leader or not. It's not really a choice. When you become a medical doctor, you're basically a leader by default. And many of the best doctors I know are A-type personalities that are extremely extroverted. They're okay working really hard, working around the clock and being around other people all the time. There are some specialties you could make a good argument that it's better to be introverted in. And these would include, you know, maybe radiology or psychiatry, something along those lines. But a lot of them, it's going to be better if you're an extrovert. Doesn't mean you can't do it if you're an introvert. Okay, I'm not going to tell you that. But just overall, that's my opinion. Number seven on the list is going to be financial advisor. Now, this is going to be a person who is employed to provide financial services and advice to individual people. So you're going to be talking to just normal everyday people that are looking into retirement or investing or things like that. Now, personal financial advisors make around $87,000 a year. There's 263,000 jobs available. And it's growing at 4%, which is as fast as average. So you're going to be talking to just everyday average people giving them investment advice and other types of financial advice, anything from investing, budgeting, retiring, paying for a house, paying for their kids college, all sorts of different things like that. You're going to be constantly communicating with clients. And it's important that you talk with them and gain their trust. This is definitely one of those professions where being able to talk to people and maintaining relationships is going to be key to your success.  Number six on the list is going to be dental hygienist. This is basically the person who is under supervision of a dentist and they help the dentist out by providing certain services that basically an assistant couldn't provide, but someone who is a little bit more trained than that can actually help them out with dental hygienists make around $76,000 a year. It only requires an associate's degree. So not too bad in terms of education, 226,000 jobs available, and it's growing at 6%, which is faster than average. So think about the experience.  They're all up close to you and stuff. Pretty uncomfortable for most people, obviously. This is why dentists out of all different types of doctors usually have some of the best bedside manner and the people they work with generally are the same way. They want to make the process of going to the dentist, getting their teeth cleaned, getting all that sort of thing done as painless as possible. That's a lot of cash. So I'm not going to sugarcoat it here. I'm just going to say this as plainly as I possibly can. Most of the successful dental hygienists are going to be very outgoing, extroverted people. Number five on the list is going to be a manager. Now managers are going to be people who are kind of in charge of controlling or administering a part of a company. So there's a ton of different examples out there. I'll give you a couple of them. Construction managers, 95,000 a year, 476,000 jobs available, growing at 8%, which is much faster than average. Computer and Information Systems Manager, $146,000 a year, 461,000 jobs growing at 10%, which is really good. So everyone knows that managers make really good money. They make a lot more than their non-manager counterparts. Software developers, for instance, make around $107,000 a year and their manager counterparts are going to be making over 145,000. And you basically see this disparity pretty much everywhere. Businesses value people who have leadership and management skills. It's just that simple. Now as a manager, you're going to need to communicate with your staff all the time. You're going to need to form relationships with them. You're going to try to foster a positive culture, hopefully.  A lot of the time as a manager, you're going to get calls after work.  Nope, somebody's going to be calling you up. That sort of thing honestly drives me nuts. I hate taking my work home with me. I like to do work when I'm at work and just relax, do whatever I want when I'm at home. But I'm an introvert. This is a list about extroverts. A lot of the time extroverts love it when people call them up or when people text them. So this is another position where, again, you can be good as an introvert, but a lot of the time it's going to help you if you were extroverted. Number four on the list is going to be a nurse. And nurses, I think everybody knows what that is. They care for people who are sick. Registered nurses are going to make around $73,000 a year, 3 million jobs available, and it's growing at 7 percent, which is faster than average. Another career where you're just going to be around people all the time. You're constantly going to be talking to patients as well as talking to doctors and other healthcare professionals. Nurses always have way too much to do. They're basically like the backbone of healthcare. And you have to be able to communicate and talk with people effectively while you're rushing around trying to get stuff done. Now on top of that nursing is one of those careers where there's tons of jobs out there. There's 3 million registered nurse jobs out there alone. And so it pretty much doesn't matter what personality type you are. Nursing is going to be good for just about any person out there. And the reason for that is because, hey, you get a job as a nurse in this one specialty, you don't like it. Well, guess what? There's like 100 other specialties that you can try to get a job in as well. Some of them are going to involve more or less patient interaction. So this is a really good career for extroverts. And in general, it's just a good career for just about anybody to get into. Number three on the list is going to be an executive. This is going to be a person with senior managerial responsibility and power within a business. And they're going to be responsible for creating this plans basically and putting them into effect. Now, BLS has top executives making around $104,000 a year. There's 2.7 million jobs available. So a lot of them and they're growing at about 4%. Now, depending on the company structure, generally speaking, executives are going to be a little bit higher than managers. You could almost say that they're the manager of the managers. So executives are going to oversee the implementation of plans that the company put out in order to make sure that they are meeting their deadlines and their goals. Now, a manager will oftentimes play the role of a motivator or a mentor to individuals within the company. Executives will often play a role of motivator or mentor to the managers. Now, there's a ton of different executive positions. It could range all the way from CEO, which is the head of the company, CFO. It could be a vice president or a president. Now, a lot of these positions will have to interact with people all the time. And so it's going to give them an advantage if they are an extrovert. Number two on the list is going to be real estate agents. This is a person who sells and rents out building and land for clients. Now, real estate brokers and agents make around $50,000 a year. There's 477,000 jobs available. And the growth is a little bit slow at about 2%. Now, one thing you'll notice when you look here is you don't have to get a college degree or anything like that. In fact, most real estate agents just have a high school diploma or the equivalent. It doesn't take long to become a real estate agent. You got to take a test, you got to get certified, and then you're basically good to go. Now, careerblist.com, basically they rank a bunch of different careers in terms of job satisfaction. I think they're one of the better websites that I look at when I'm looking at different methodologies and stuff like that to figure out which jobs have high job satisfaction. Careerblist a few years ago ranked real estate agents as the happiest job in the United States. They had it at 4.26 out of 5 in terms of its total ranking. Now, technically speaking, a lot of real estate agents are salesmen, but it's more of a chill, long-term type of sales. It's not like a pushy, get people to buy sort of thing. It's more of a formal relationship with them, get to know them, figure out what they need, and then help them out in the process of selecting a house. A lot of successful real estate agents are just people that are very well connected in their community, and then whenever someone decides to buy a house, they're like, oh yeah, John that I go to church with, he's a real estate agent. I guess I'll go and call him. A lot of the job is just hanging out with people, going to different events, and being well known within your community. Now, a lot of people choose a more laid-back approach like that, and then some of them get a little bit more aggressive, and they do things like door knocking. And that's basically where you spend all day just going to random houses, knocking on people's doors, and asking them if they're interested in either selling their house or buying a house. Again, a lot of these methods would likely give a slight advantage to extroverts just because of the fact that you're going to be around people all the time. You're probably going to be meeting new people all the time, and so that's something that an extrovert would be a little bit better at just because of the fact that they get energized from that. Number one on the list is going to be entrepreneur. And this is a person who organizes and operates a business, generally taking on a significant amount of risk in order to do so. So obviously, the amount that you make can vary a lot here. There's entrepreneurs like Jeff Bezos that make billions and billions of dollars a year. Now, according to data from BLS, approximately 20% of new businesses fail during the first two years of being open, 45% during the first five years, 65% during the first 10 years, and only 25% of new businesses make it to 15 years or more. Now, these numbers are generally for small businesses, so things like opening up a barbershop or something along those lines. Those types of businesses don't have as much of an upside. You're probably not going to make any more than maybe a couple hundred thousand dollars a year at best with a barbershop. And so they have a much better chance of success, whereas if you get into something like a startup, for instance, like starting an app or something along those lines, your chances of success will likely be a lot lower. Startups, for instance, have an estimated 90% chance of failure on average. So yeah, you definitely don't have to be an extrovert to be a successful entrepreneur. There are many cases where introverts can be successful as well. A lot of it depends on what industry you're in, who you have in your team, what type of business you're running. But in many cases, it's good if the company has someone who is kind of a charismatic leader type of figure. An extrovert might be better at coming onto a shark tank, for instance, in pitching their product. They might be better at recruiting and leading people on their team. They might find it a little bit easier to network with other people who they might potentially end up doing business with. Make sure to smash the like button, hit the subscribe button, ring the notification bell, comment down below any thoughts, comments, criticisms, etc. that you have on this video. And before you go, make sure to always check out my other videos right here because I made them just for you.


T. F. N. N. Deadline news update. Hi everyone I know it's hard to believe but we've got the doubt down at the close today, early close at one o'clock. Easton Time, this is Basil Chapman, the host of the Tiger Technicians Hour, just finished the show noon to 1 p.m. and the author of the opening call. The dial's down 35 at 28,515, needs to go above 28,600 to make the next leg up and the S&Ps are barely down, it is fraction down down 64 cents at 32,23.37, it needs to go above 32,27.78 to start a new leg to the upside. We've got the QQQ, that's the NDX100 trading vehicle, right now it is trading at 211.99, it needs to go above 212, I think it wasn't, oh is that, there it is, 212.52 to start another leg to the upside which I think it will and the IWM which actually went to a new recovery height today at 1.66.64 up 34 cents is sharing nice relative strength, gold had a really strong session today, gold is up $15.00 or $15.04, it really just smashed through that whole resistance in the 1292 area, this is good action and the silver also went very sharply higher, silver is up .33, remember yesterday silver led the gold and the metals market higher, it's a 17.82 up .32, that looks like the 18s, it's going to try for the 18s very quickly and now you've also got, I wanted to do the dollar, the dollar was down just a couple of pennies before now it's up a penny, $97.68, it is holding really well considering what the metals are doing, crude oil, I didn't do crude oil in my show, I forgot but crude oil is up, it should go higher to another leg to the upside, we're looking for that leg D in the Chapman Wave methodology above $61.40 in the continuous contract, the TLT also had an update up 37 cents or $136.82, money will probably start to flow into the bonds if you start to get really sharp moves to the downside in the market and there's bad news to accompany with that. Meantime back at the ranch, what we're looking at is markets holding the other all-time highs or at all-time highs and let's see how it goes into the end of the week, have a wonderful Christmas and a wonderful Hanukkah to everyone celebrating and we will see you back here at TFNN on Thursday, Larry Pesaventa kicks this off right early on at 9 a.m. Have a wonderful holiday.


From my personal experience and my, you know, so many years of dealing with a lot of instances and those moments, luck is something I go with my preferential, you know, my favourite quote that when preparation meets opportunity is when you call luck. Having said that, I think it's a very important fact on any performance which you are into, I mean whether it's sports or whether it is in terms of presenting to a client or, you know, any particular meeting, an interview or any of those because it's about how you're prepared and you never know when the opportunity is going to come and when you get an opportunity, how well you're prepared is something that can convert to a good luck. It's also important that, you know, sometimes when we want to really go and try that hard, it's also important that the nice fact that, you know, a kind of energy and the impulse that you have and to create that, you know, there are certain mechanisms in which, you know, everybody has got their own tricks or their own ways to get each of those. So it's a combination of all of this. So that's how I define good luck and success for how success, etc. comes from a good luck perspective of many of the individuals. I had a good mixture of good luck and bad luck. It has happened in both forms. Personally, you know, if I want to really state an example of a good luck is, you know, when you get on to going to see, going to get into a tennis match and then you go on with a lot of, you know, analysis and speculation that you're going to meet a tough player and then fixture gets drawn and you, you know, you actually get to play a little bit less tougher player and especially prepared well, you're able to really, you know, rejoice at that moment as a good luck situation, right, which is also a kind of a bad luck for the person who's playing against a better player. So it's a mixture of things and I've had this instance in good and bad. I'm very happy and to say that, you know, unless and until there is always a mixture, it just allows you to keep at it in your preparation and you never know when the opportunity comes that it plays on to you for succeeding many things in the future.