Hello everybody, Andrea Mayeski here with dental L tutoring. So this is kind of like a part two to a video that I had just done. But there's going to be more parts here where I'm just, I'm, I'm just talking about crazy things that patients do and say and how I react inside my head and what I actually say to them, okay? So, sorry, I thought I heard the mailman here. So listen, is it actually nicer to keep the window open kind of a or is that too much light? Maybe it's too much light. Okay, sorry guys. Okay, so this actually happened to me. So you guys probably don't know, I don't know if I talked about it, but I have something called psoriasis. Okay, so it's it's a skin condition where the cells are just over producing and if you have that too, it's similar to eczema. So if you guys have seen that, in fact, I have it on my elbow here, which might be kind of hard to see from all of the lights. But it's it's it's like red white patches. Okay, honestly, no big deal to me. Hey, things could be so much worse. But anyways, so but sometimes it does get a little bit bad where it's more obvious. Like I do have it on the backs here, but sometimes it can kind of like creep up here. Okay, thankfully, that's it. Like I might have a little bit here sometimes, but I can cover that up usually with makeup. But sometimes it's just a little bit more obvious. So I had patient once. Okay, he was in 60s. A nice man, you know, you wouldn't really think anything of it, but he really wasn't that nice. Okay, this patient actually came in. I'm bringing him back. This was at an older office where I used to work, so I don't work there anymore. They had weird patients. But anyways, so he comes in, I'm, you know, saying you're you're in for a cleaning today, any changes in your health, any tooth issues, you know, so just kind of talking to the patient. And he says to me and he looks at me like, Whoa, what happened here? Because I did have psoriasis like here that day, which again, I think I'm just used to it. So I don't really even realize sometimes how it looks to people because I just think, hey, whatever, things could be so much worse. He goes, Oh, what happened here? You know, I thought he was concerned, like maybe he thought I had a rash or something. I go, Oh, that's just a little and at first, like I wasn't sure I was like, Oh, what happened? Oh, that I said, Well, that's just a rash that I have. It's a skin condition that I have.   And I said, Oh, wait, sorry, no. Well, I do, but it's not contagious. It's just something that some people have. You might know it as, as eczema, you know, that's how it looks. Because usually when I say the word psoriasis, people go, Sorio, what? Huh? Like they have no clue, right? So I say eczema. It's just something that people seem to understand more. It's no big deal. But anyways, he goes, Oh my God, is it contagious? That's seriously how he looked at me, you guys was and like he backed up a little bit. I said, and I laughed actually and said, No, it's not contagious. If it was contagious, I wouldn't be allowed to work here. I'm a healthcare professional. Duh, that's what I'm thinking. He goes, Oh, oh, okay. And like he looked concerned, you know, I couldn't feel bad for the guy.  Seriously. So I said to him, I said, Well, if you're concerned, I don't, I don't want to make you uncomfortable. I would be happy to rebook your appointment. I'm the only hygienist here today. So I can't just give you to somebody else, but I'd be happy to rebook. In fact, I didn't want to see him. He was like, Well, I can't rebook. I'm here now. And I said to him, like, Well, you look really concerned. How about we rebook? So I don't make you uncomfortable. And I made notes, by the way, in the chart, saying like to rebook. And then I gave him the option because wait till what happens next. So he was, he seemed fine, you know, throughout the appointment.  He actually called back a couple days later. He called back a couple days later, talked to the receptionist and said that last hygienist that I saw, she gave me an infection. I was in the hospital and had to go on antibiotics because of what she had. That's seriously what he said. I was so insulted when I heard that. I don't even remember who told me this actually. Oh, I do remember. I didn't find out about it until his next cleaning appointment. When the other hygienist who worked there, she's so nice. We talked a lot. She actually saw him because I wasn't there that day. And she had noticed notes in the chart from that phone call. And she sent me a text saying, you won't believe what happened.  But also maybe they didn't tell me because they didn't want me to feel bad knowing how pissed off that I would be.  But so maybe that's why. But in the chart, in the notes, it didn't actually say anything about, you know, how they told him it's nothing contagious. If the hygienist was contagious, she wouldn't have seen you. So in the notes, it didn't say that. I don't know what the conversation was, but you'd think if they said that to him that would have been in the notes. All the notes said is what he said. So I don't know how the conversation went. And when I tried to talk to them about it, they couldn't remember. And I kind of, so anyways, that seriously happened, you guys. I wish I was still working there and that I did have them in my schedule and then I could have said to him, Oh, I'm that same hygienist that you said you got an infection from. I can't see you today. I wish that happened because that would have meant that I would have had an hour opening and I would have pissed him off. So that would have been great, but I don't work there anymore. It's not crazy, you guys. So that actually happened. Where do people get the nerve seriously to say things like that? So be careful. If you're ever having a bad air day, if you have a skin condition, if you don't look totally normal, your patient might say something to you and say you have an infection. Who knows? Yeah, that seriously happened. Okay, let me think of something else to quickly end off this video with. Let me think of some weird things that patients have kind of said. There's been a lot of weird things. Oh, let me think. Okay, this is a good one. I had a patient the other day, 17, 18, you could tell he was full of himself. Like he just kind of stood there the way he talked. He thinks he knows everything, right? So I would say things to him, you know, because as I clean teeth, I do talk at the same time. So I would say something like, Oh, there's a lot more plaque on your left hand side here. So that's showing me you're not brushing as thoroughly on that side.    He kept saying things like, How do you know I have more plaque compared to last time? How do you know that? I kind of looked at him like, Well, I was looking at your notes from last time, and that's what it says. Yeah, but you didn't see me last time. I saw somebody else.  Oh, okay. Okay. And then, you know, and then he said, plaque, you keep talking about plaque. What is plaque?  But when you ask like that, like, Okay, okay, you keep talking about plaque.  It's not something we talk about every single day. We do because we're dental professionals. But you know, teenagers, adults, kids don't just talk about plaque, right? But he was being rude. So he's so that's what he said. He said, So what's plaque. So I talked about it, you know, plaque is that stuff that forms on the teeth pretty much right away, like eating, drinking, it could be yellow, it could be white, you know, it just depends too on the food that you're eating. And if it's left on the teeth too long, then it then it forms tartar. He goes tartar. What? Oh my God, kid. Oh my God.  You know, again, I don't mind explaining, but when you react like that and have that attitude, I'm thinking who heck are you, right?  That's what I want to say. Seriously, only patients knew what we want to say to them. So yeah, this was the conversation. But the kicker was, which I forgot to mention, sorry, all in his chart, like on the computer in the paper chart, it says do not use piezo. Or like, I think it says do not use the water instrument, you know, something, right? So I'm like, okay, this kid doesn't want us to use the water instrument. When I sat him down, he pretty much said, Uh, yeah, hi, don't use that thing that sprays water, you know, and like, he's not looking at me. He's just like, Yeah, don't use that thing that sprays water please, you know, so I'm thinking he's just nervous. So I'm, I'm, I am okay with that.  I can just use my hand instruments. Fine. You know what? Fine. People are weird, but that's okay. But he had a lot of tartar and staying lower anterior lingual. So I actually said to him about halfway through, I said, Um, is it okay if I use the water instrument only on the bottom teeth? Because there's a lot of plaque there. There's a lot of tartar. And I think that's how we started talking about plaque and tartar because he didn't know.  But with the water one, like I can just quickly do it. And that's it. And then he says to me, What? What water thing? I'm kind of like, did he not hear me? So I said the water instrument that you don't like. Is it okay if I use that just a little bit? And he said to me, How do you know I don't like the water instrument? I'm like, I could have sworn that's what he said at the beginning. It's all over the charts. So he said that to other people. So I said, um, the piezo, the water instrument that we have here, um, that you mentioned at the beginning that you don't want me to use. He goes, Well, why are you telling me this? I'm so confused. You guys, I didn't know how to respond. So I said to him, Well, I'm telling you because I'm asking your permission if I could use it on the lower front teeth because you did tell me not to. And I respect that, but I need to use it on the bottom. So I'm just asking you if it's okay first. So he says to me, Oh, yeah, sure. Okay, so I'm using it. He was totally fine, you guys. So I don't know what the heck was in the chart, what he was talking about. He was totally fine. Um, usually I clean like a tooth first or like three teeth and then say, How is that so far? So I said that like after using the piezo and he said, How's what? The water instrument that you don't like. He goes, It's fine. Like, Oh my God, it was the weirdest patient appointment ever. Okay. So sorry, that took a little bit longer, but I hope that this is making you laugh. It's actually fun to talk about because these things really happen. So thank you guys for watching. Stay tuned for some more. Make sure make sure to subscribe and I'll see you guys in the next one. Thank you.


All right, welcome back to entrepreneurship Tuesday on why and the morning my name is by Moses or it's by one social media And it's time for our first interview of the day This gentleman right here has been from University to a music group and now doing his own thing He goes by name Utikas, which means patience and is here to share his story with us. Thank you Oh, you can introduce yourself just in case you missed anything. Yeah, my name is Utikas But I go by the name fortunate Utikas means fortunate.  That means I double in a lot of Fields and my gifts here. All right. I'm so happy to be here I always like to have people like you on set people who have different gifts and Explore their different gifts. So your t-shirt is Is you unit? Yeah, this is your merchandise. Yeah. Yeah, and fortunate is your knee. Yeah. Yeah All right. This is I see a 1% on the side. So fortunate 1% before we talk about anything I don't know. What is this about? the 1% like In every society We you'll only see that these the lucky 1% like the people the elite the people who have it and Sometimes it's a fad dream. We have the American dream the Kenyan dream But only 1% people get to achieve that. So the concept of 1% is all about that All of us are made for greatness. It doesn't mean that Those 1% that are out there the people who have it that you and I cannot get there So it's much more chosen to be that one. Yeah, sometimes if you like Yeah, you can it's actually a philosophy that I I may not be the best I am because I'm 1% it means I need all these other 99% still I still need them because we don't leave as Islands. Yes, we need to coexist. Yeah, we to coexist and so the aspect of 1% is much more You as I individually and being you Deciding to be I won't be part of the statistic But I'm where I am and I'm fortunate and I'm loving it though I may not be where I want to be I know where I'm going you're fortunate to be that one person Yeah, one of the powerful words right there. Thanks.    Yeah, you have been part of the music group and Out of all these things I've mentioned. I don't which one comes first the music group or campus. Take me back So we so I finished school 29 2010 We started a group called 3 4 12 Mouhanji Clive Jimmy D Milome Milome. We actually went to school with Milome. Oh, yes, you went to the same high school. Wow amazing so after that we we did music for around six years and It was really good at that time. I was still in campus and I finished campus I started working still doing music and It was really a good time And I think we made memories and friendship. How did you guys actually link up tea photo?  Sure.  All right. So you say Things that you do in a group Will help you But always know that you are responsible for what you do at the end of the day So know where the group comes in and know where you as an individual you coming. Yeah, all right, and I've come to learn that Life is like water. Mm-hmm. So I enjoy the moments I have with people. Mm-hmm. So When I was in a crew, I loved it Like I believed we'll do this till you are seven. Mm-hmm. But now that I'm solo. Mm-hmm. I'm loving it You're loving it as well. Yeah. All right. I'm trying to imagine you as a teacher as well and still making music How was experience like? Okay, it was interesting I Like I used to teach about adverbs and proverbs But it was really interesting because I could use the music In the class setting so we're talking about pronouns. You're still telling the person Yeah, this is how you do it in the first person second person third person and It was really interesting. I really liked it, but I Found myself sometimes not really talking like I would find myself drifting to stories sometimes Telling people more about imparting them more than really teaching but teaching what is required of you in the outline? Yeah, I did that. It was like but I really love the one-on-one session. I hope your employer is not watching right now I know Okay, he was watching perfect because I really loved the offset off teaching sessions Like after teaching then I will come and talk you and you Get to connect the students talk about life. That was the part like I loved the lessons But I loved the after lessons. You love the after lessons. Yeah, did they connect with you differently? Do you feel like the students connected with you different from the other teachers in your in your surrounding? Yeah, I am person being somebody with that music quality and you know, it's very easy to teach with music to learn Yeah, so I think One thing that really made the students feel like I was one of them is because I was young. Yeah, and Funny enough it like I taught first in a girl's So it's really comes with it It was a challenge, but like principles and you can't do some stuff. Yes, but Principles only extend to you.  So I had to make sure that I keep What like what bought me there there? All right, so it was we are not even talking about your business yet And I'm already learning a lot from you When it comes to group dynamics, you need to understand your role as a person sure sure And when the group comes in true principles are very important. Yeah, so so far. I have those two two gems so Understanding your power as an individual. Yeah in the group dynamic. Yeah Did it help you to get to where you are today and is it the reason you're doing what you're doing today? Yeah, I think Understanding that all right We're in a group yeah, but first to survive I need to provide this this this and that I need to always be active and provide this this and that At least some of the things you're doing for yourself right now and did it impact you post it Well, I never thought I'd never answer this question ever and but for real it was because We had a mentor and a producer called gala and he would give us advice do this do this and Sometimes his advice would stop then we have to do the work, you know at the end of the day And we had to now get to learn the links where to do the branding where to get to hire stuff How do you organize an event? How do you organize a shoot? How do you organize a shoot? How do you talk with corporates? And those moments are the moments that really even channeled us to where everyone is right now From black like because I had to now find out what are we dressing? So if what are we selling for much? Where are we? Where are we getting them? So by then we started with wristbands. So we started with wristbands the most simple simple form of merchandise And guys are like, okay, then they started buying, you know at that time wristbands were nowhere Like you couldn't get custom wristbands. So that's where we started then we now started We went to pendants with the t-shirts then slowly by slowly other guys started asking for them and The rest is history business group. Yeah, the business group. All right So over time you learned a lot of things during this process. Yeah, and now you have You have your own productions. Sure. You're producing for yourself. You're producing for other artists You're co-working with other producers. You're into branding and the branding aspect grew for sure I'd like to talk about this Transitioning from having a music producer to now producing for yourself. How is it like? Well, it's it's really I Can't say that I'm there yet Because I have a like the partner. It's called wrong. It's really talented Superb is really good with the making beats and all and the engineering So I usually do like mostly of the art directing the songwriting part make like the producing part No, the sound engineering and all the other. Why yeah, let me not get you lost in the details Okay, I think I'm lost in here. No, no worries Production transitioning from having a producer to now directing your production having your own producer with you rather Yeah, so after we took a break from the group. I was able to get I was fortunate to join Nile up so we were told all about business models and We were able to know like restructure our businesses then I I We did your crowdfunding. It was my first time It was really which platform did you use to do crowdfunding? It was called It was called next economy next one. Yeah, it's led by Nile up. So with What we were able to get we bought a Microphone and that's how we started. So we are also like planning on now increasing our Output and doing more and all right and investing more in the business. Yeah. Yeah All right. So crowdfunding was a source of capital. It was a source. Yeah, all right Does it work? Yeah, it works. It worked. It worked. All right. Yeah, people who contribute Contributed do they follow up in the in the business? Are they all are all up in your space asking? What are you doing now? They're really They're really cool and unco signed Partners because they're really involved like if I put out anything out there. They'll be the people that will Yeah, they'll ask What have you done with this? How are you? How can we help you in this? They're really instrumental and I really value their feedback and their relationship. All right. I recently had guys Who are trying to to bring this crowdfunding concept in the country? Because they realized most of the people with ideas bunks don't like us man So crowdfunding is a future for Kenyans who have ideas What are some of the tips you can give somebody who's looking to raise capital this way? I can okay because I Can say mine wasn't as successful, but I learned something out of it, but mostly say I Really focus on The important things the important thing they put like what do you need because I Had this audacious goleani Audacious like Able to get a think is it was it one percent or two or like ten percent of it of what we had planned for so and That was able to get something so if if Sometimes if it comes to crowdfunding either reduce your Look gets to focus on what is there really the most important thing yeah, don't expectations Yeah, yeah, and Expect help from people that you don't expect. All right. Yeah Expect control be able to manage your expectations through you put it perfectly. Yeah manage your expectations and And You'll get help ready for surprises. Yes surprises. Yeah All right Remember you're on white by four channel on Twitter white by four underscore channel on Instagram I'd say four on Facebook and this is that day that the BB I report drops and we have we have a question on Facebook for you guys What are you expecting in this report and do you think it's going to impact us the way? It's intended to that is on Facebook We are looking forward to your feedback and we'll be sharing them with the world towards the end of the show So my guy, yeah, let's talk about branding now, which is something You're really passionate about sure you started quite simply without even knowing your brand Yeah wristbands you wanted t-shirts, but now you're doing it for yourself and other clients. How was it like? It's really a good experience and a space to be in and the process of creating because You know Okay, what's failed me and You can have a client can have this concept then bring it to life And the process of bring what they want to life is really I love that process So when someone says I want this t-shirt looking like this or I want or I want to achieve this But I need some branding on this line So it's really the process towards that is really what I really enjoy They changing and all that and making it Sometimes we are supersede what they wanted. All right, so it's really it's the process is what I really like the process is what you really like All right, so Some Corporates or some people have been accused of being very good at branding. Yeah Average products yeah, the product is not so much but the branding is super true true true and when you do this you run the risk of achieving Very good first week sales when it comes to music you have a good chance of achieving very good Launches, but in the long run. It doesn't happen. How do you manage to to to balance the product and the branding? I? Think using the the 5p is any like the product the price is Mostly the product and the price and the value that the people want because that's where People fall short so they want this price They want this value, but the price is way up and Sometimes you have to reach our consensus like this is what you want and this is what I can offer you and sometimes I notice some if if we don't get this clear way before these are things that really come back and They really hurt you they really hurt you really like I've really like I've had situations where I Someone was like I want this at this price. So I went Like when you put the value like the price before the value sometimes really Get to hurt yourself. You hurt yourself as a business person Sometimes even emotional Why then you like why did why did we start all this all together? All right, so it's sometimes just Having to understand this is what you want and this is what will cost you and this is what we can go for This is what we can get. This is what I want. What I want is always here. Yeah What you can get is always somewhere here, and then what you're going to get is always so It comes back to what you said managing expectations So how do we bridge this discrepancy between what you want and what you get? How can we make it really seamless? How can we bring it to what you want? This you can only learn over time. Yeah, it's time. Yeah, let's get a taste of what you do in living color So maybe if we can get some pictures on the screen to show us What I would rather you take us a.k.a. Mr. Foshige does as I said But remember we are on Facebook at white 5 4 on Twitter at white 5 4 underscore channel and on Instagram on Instagram at white 2 5 4 Channel. All right. So this is you right here. Not In that sense, this is your work right here. Yeah, all right. So what is happening here? So this is this is a poncho It's not yet. It doesn't have any brand. So usually we create Samples, yeah samples then if you want now to get it branded Like maybe your name or your company or your logo now. That's when you take it the way father All right, so this might end up with a company logo.  Maybe it's a mantra that they live by or something. Yeah So someone will really put their name, but they can Something about something that speaks speaks for them speaks for them. Yeah All right, I feel that this is also another sample, right? Sure. Sure. All right. Who's taking the pictures by the way? These are the pictures that you send to clients. Yeah, I do. Yeah, show them the samples that yeah, yeah, who takes the pictures Okay, I walk with several studios and several photographers. Yeah, all right. So you got sauce when it comes to that Yeah, yeah, all right in our soon God only So this is also sample forget including the hat. Yeah. Yeah. This is another one. Yeah All right, this is this is my favorite so far the brown one. Yeah, the brown jumper right there That is my favorite so far. This is also a sample. Yeah, it's just somewhere. All right. Why don't you just turn this to a clothesline? Baby steps baby steps. Yeah. Yeah All right, so we need that is a lesson you've also learned in the course of doing business. Yeah, all right So baby steps you need to wipe baby steps Why not just go in because you always told take take risks in business I'm learning. Okay. I was reading this book. It's called contagious and Why things why things catch on and sometimes it's Those things that you don't expect that may make things catch on so I'm really Working on that space and I'm not forcing myself into it. All right according to this book contagious Yeah, after reading contagious. Why do you think gang it on really caught on to? the market right like that there's the aspect of being hip people love talking so they You want to be in the know like for example yesterday The the the lady pastor who did the video So like everyone wants to share it so that they can be in the know share ability Yeah, like you want to you want to be the person who knows and those are like they are Seven and we can't talk about them But like now that the social capital that comes with you being in the know All right, it's really so if your product has that talk ability here talk ability and that Controversy around it. That's just one aspect. It's a lot of aspect like the aspect of people want to be Ascribed to it. Why people want to show Like why do why would people why would for example we in Kenya e pz. We We do calving train In e pz. We do leave is in e pz. But they go out there then they come back, but when you but We don't even think that these things are made in Kenya know about that. This is okay. Yeah, so we we it's the aspect of It's emotional it's spiritual by the way, so you need to connect with this year and it takes a while That is why baby steps are very important when it comes to business. Yeah, baby steps and and I think also Putin god any like there's a lot of this. This is really a very strong Spiritual aspect that comes in business that we don't all right. And that's what even makes Some people tick and some things not work.  Yeah These your resident models. They are very good friends of mine and partners. We work with them like I work with them on Very different fronts. Mm-hmm. Like for example this She's called one boy. She does beads. Maybe you can see them like she's the one who does the beating and then it's Sylvia She's she's one. She's also a partner in what we do. All right. Yeah, wonderful, man So I think we've captured every aspect them all But at least they got a taste of what's happening You have captured the aspect of your music in your business the branding aspect You as a person But as a minister of the word, I know it's very it's very unfair for you for me to let you leave without speaking something About about your drive and about the Reason that you do this thing and the reason you do this thing is to win souls To the Kingdom show show for the King. Yeah. All right. When when when did you actually get this? What do you call it? The light. When did you see the light? I? Think I've always been there like the black sheep in the family and How convenient and I can see I Through the motions, and I've learned that Sometimes we don't play what we believe it's it's very All these other people who in business for example The other day we're talking in church and they were saying like when you go to all these other people if it's a Hindu if it's an like they will always put their religion and they put their religion affects their business and also I think as being Christians we need to Also, let our belief affect our business yet as Christians. I believe I also apologize We have really failed in this just for really failed business and church are different He and for example, you'll you'll find that Even our prices are very exuberant. You see It's very capitalistic. Yeah, like we don't Like we'll say about loving your neighbor But when it comes to business, you're going to overcharge that you love a child and neighbor So it's we there's a discrepancy between what we believe and they will believe and we'll give our neighbors expensive loans We'll give our neighbors Overpriced true products will give our neighbors Bad quality stuff, but when we look at other religions, we can improve it on this Yeah, we see how the Muslim religion affects their businesses They they close shop during Ramadan.  It's it's worship. Like what you do is still worship everything that we do bury you as here as you as you As you enlighten the people as you give them Awesome Yeah, as I informed as informed like You still it's still worship. It's still worship.  You're going to take my job for so we can play it and Before introduce the song remind them your social media handles and the business social media handles Sure, then introduce the song so we can wrap this up Yeah, my name is Utikas tapkins.  I still go with T4 12 Facebook is Utikas fortunate tapkins.  You forgot the most important YouTube channel or YouTube channel Utikas just Utikas Utikas, please UTI CHU UTI CHU as thank you very much. Thank you. Thank you to why in the morning. I really appreciate you We're going to be listening to his song. He has a lot of voice words to say and I'm pretty sure it doesn't change in the music So we've come to the end of this remember on Facebook We have a question what are you expecting in the BBI and do you think it's going to affect us or the intended way? We are looking forward to your feedback. We are going to be sampling it Towards the end of the show. My name is by Moses or it's by more on every social media platform Alex is coming up next with another interview. You don't want to miss it


Hi, I'm Zor. Welcome to Nezor Education. Today I would like to talk about using semiconductors in electronics primarily to make diodes. Now diodes, as we know from previous lectures, are such electronic devices which allow the current to go only in one direction. So if you have some kind of a diode that has basically two ends and if you put electricity plus and minus in one way, the current will actually go through. If you change the polarity, the current will not go through. Now before we were talking about implementation of this particular device using electronic vacuum tubes and obviously you're welcome to go to the previous lectures where it's all explained. Now it's a completely different concept based on semiconductor activity which will implement the same functionality. The current will go only in one direction and if you change the polarity, it will not. Now this lecture is part of the course called Physics for Teens implemented on Unizor.com. Well Unizor.com is an educational website where you can find another prerequisite course, mass for teens. So I strongly recommend you to familiarize yourself with all the mathematical concepts used in physics and mass for teens course provides it. Well and obviously it stands by itself at the course of mathematics. What else? Well the site is completely free, there are no ads, no strings attached, you don't even have to sign in if you don't want to. Okay now this lecture actually is preceded by another where I basically explained what is P type semiconductors and type semiconductors. I will briefly repeat this type of thing in this lecture but again I strongly recommend you to to take the course basically where where all the topics are linearly related and logically related to each other. Okay so we're talking about diodes implemented as a P-end junction. Okay so let me start again from very brief review of what semiconductors actually are. Now consider the atom of silicon. Now the atom of silicon has a certain number of electrons but we are concerned only in electrons which are on the outer orbit which is called valence electrons and there are four of them. One, two, three, four. Now also there is another very important thing that atoms are trying, well as if they're some kind of integers with this mind, they're trying to have eight electrons on their outer orbit, valence electrons and well obviously it's not always possible because right now we have certain number of protons inside the nucleus and certain number of electrons and the outer orbit contains only four but if you have another atom of silicon nearby and each of those atoms also have four electrons then what's very interesting these pairs of electrons serve both atoms this one and this one. Well you can say that they are maybe rotating around some kind of a midpoint or I don't know really how it is actually arranged inside but now this one can count four of its own and four of neighboring electrons and this one also counts four of its own and four of the neighboring electrons. These are related to each other with some kind of covalent bonds so this is a concept which I have explained in the previous lecture so there is basically it's like a force if you wish which forces these together and basically count as valence electrons for both this one and this one and this pair is for this and this so these covalent bonds are holding much stronger the whole structure basically enabling crystalline structure of the silicon as a material so that's all about silicon. Now let's talk about semiconductors in case of semiconductors we are introducing certain impurities into silicon so sometimes we are replacing certain atoms of silicon with atoms of let's say phosphorus. What's important is for element which we are adding is to have five electrons on the outer orbit five valence electrons so what happens well these four will be related through covalent bonds with neighboring atoms and this one will not have any covalent bond but obviously there is a bond between this electron and the nucleus nucleus has also corresponding number of protons same as number of electrons so there is a positive to negative attraction obviously that's what keeps this particular electron near this atom but not as strongly as all other valence electrons because all other are also connected through a covalent bond to a different atoms of silicon in this case this is also silicon and this one has no covalent bond so it doesn't participate in the crystalline structure that's very important now another kind of impurity which we can introduce is when instead of four electrons we have three boron element boron has three electrons in the outer orbit three valence electrons one two and three these are connected but this electron of the silicon has no covalent bond connecting to this one so again this one is held only by its attraction to the nucleus and not by any covalent bond so basically you can say that this is some kind of a hole if you wish now the crystalline structure and covalent bonds actually are very strong and sometimes what might happen is let's say this particular electron since it's still you know on the outer orbit if excited by something like heating or or applying some voltage for instance it can actually start acting very very actively and it can jump and fill up this particular hole but that would make this hole now so we will restore the covalent bonds in this particular case but this hole will jump to this particular thing so we're talking about holes as basically absence of valent electron but in this case again the hole might actually migrate it might move from one place to another that's all about how semiconductors are arranged now if no excitement introduced into this particular picture no heat no external voltage no sunlight or whatever else can excite electrons well the whole thing is neutral even with impurity because impurity has less protons in this case and less electrons in case of a phosphorus for instance we have an extra proton and extra electrons so the whole thing is electrically neutral however existence of extra electrons or extra hole in the whole structure actually makes certain differences when some some some activity actually is observed if some excitement of these electrons can be observed based on as I was saying heating or sunlight or electric voltage etc so those semiconductors with impurity that introduce the extra electron is called n-type and those like boron for instance where there is a deficiency of electrons in the structure in the crystalline structure they're called p-type n stands for negative p-type stands for positive because hole can be considered as a positive charge well the electron is negative charge the same thing as in any other electrical kind of thing what is positive positive means it's it's lacking electrons deficiency of electrons so the whole is like a positive charge so we have p-type and n-type now what happens let's say let's talk about b boron introduced so it's a p-type semiconductor what happens if I will apply plus and minus to the whole body of semiconductor well let's just think about it we have basically two important forces which are acting in this case but in any case one force is the attraction between positive and negative charge so protons for instance in the nucleus are attracting electrons around at the same time we have covalent bonds which are also holding electrons together and makes the crystalline structure at the same time we have plus and minus here which are also kind of attracting plus attracting electrons minus repels electrons so what happens in this particular case if the voltage becomes stronger and stronger well if it's very weak nothing happens but as soon as we are trying to increase the voltage a little bit what happens well electrons can actually be attracted so what happens in this case let's say this electron is attracted here now there is a hole in between right instead of this electron there is a hole in crystalline structure now the covalent bonds are strong and some other electron can jump and replace this so this becomes whole this covalent bond becomes whole now we have we do have already some whole so the whole actually will move and this whole will also be filled up by some because there is a general movement of electrons towards the positive at the same time minus provides certain supply of new electrons so as soon as certain number of electrons migrated here this becomes the whole thing becomes positively charged and attracts electrons from minus and they will replace certain places here and to make certain things whole but plus will still continue doing what it's doing so again the holes the electrons will move towards plus and the holes basically will move to an opposite direction the stronger the potential difference between plus and minus is well the faster the more intense this process will occur so there will be an electrical current so that's why they're called semiconductors in it's in a weak difference of potentials there is no current but so it's not really it's it's insulator but if there is some kind of a excitement pressure it becomes conductive okay now what if it's n-type but it's n-type so we have a phosphorus and extra electron here well same thing electrons there are extra electrons that will go here and now this becomes positive because the proton inside extra proton is positive it lost this electrons so it will attract electrons from here so again we will have the electrons are moving with proper voltage this actually occurs that's why it's called semiconductors sometimes if it's if it's a small voltage it doesn't really conduct electricity but with a substantial voltage and substantial I don't mean hundreds of volts we're talking about three five this type of voltage the and obviously it also depends on how much impurities we have introduced how many extra electrons or extra holes in case of p-type or n-type we have the more holes or extra electrons we have well the better conductivity will be okay and now we will consider this junction think that's the purpose of this lecture what happens if we will connect together so let's say we have this p-type and this n-type of semiconductor which means here we have extra electrons extra electrons which are not participating in construction of the crystalline structure not bounded by covalent bonds so if you have something like a phosphorus added to silicon we have these extra extra electrons which are not engaged into any kind of a covalent bond so they're well they're not free because they're still attracted to its own atom but with a small push small activation they might actually jump and even in a normal condition these balance electrons which are not really bonded together by covalent bond into a crystalline structure they're still fluctuating not a lot but but still now on the p-type we have holes which I will put as pluses because again plus means lack of negativity lack of electrons so there are certain holes here throughout the whole body if it's a boron with silicon boron has only three electrons on the outer orbit so we have whole basically so you see this covalent bonds and electrostatic forces between plus and minus both are participating in this game so what happens now if nothing if no voltage is applied anywhere well there is certain migration as I was saying just random walking of these extra electrons because they are not covalently bonded with other electrons only the electrostatic forces and they're not as strong so if there is certain degree of activity some electrons can actually jump here now what happens well they are disappearing from here and they are converting into neutral from the covalent bond viewpoint atoms in the border line near the border they fill the holes now strong forces covalent bonds are holding these electrons as soon as this electron jump here well the covalent bond actually is formed and it's well relatively stable it doesn't move any further this particular electron because it maintains the crystalline structure of the semiconductor on the top of the p-type okay but what happens with electrostatic forces since electrons move from here to here and are held here by covalent bonds this thing used to be neutral right but now it becomes negative because the electrons are moved here and this becomes positive so the whole thing now becomes electrically charged okay what next well this negative charge prevents new electrons from moving further so there is certain layer of negative charge formed by those electrons which jumped and were captured by covalent bonds and there is certain positive charge in the area near the border near this junction on the end type and the process actually ends doesn't really move any further there are a certain number of extra electrons here which are filling up the holes and there is a certain lack of electrons here but we don't really need them to maintain the crystalline structure because they did not participate in the crystalline structure it was an n-type it was an extra electron on each atom of phosphorous so the process ends now it happens well let's say we put plus here and minus here attached some kind of contact well now we have introduced yet another electrostatic force this is plus this is negatively charged so the electrons actually now might move there well if the voltage is sufficient enough because again covalent bonds are still acting but if this attraction is stronger than these extra electrons will move towards the positive and go to whatever the batteries now what happens well now this becomes again positive not positive sorry holes doesn't become it becomes neutral electrically neutral but but the crystalline structure remains with holes because these electrons which were used to basically put the structure together will will migrate towards the plus which means that there is no more barrier of electrons here and extra electrons here can continue this migration and fill up these holes now this becomes again well it used to be positive now it's even more positive but we do have a source of electrons because this is a negative so this is positive this is negative so electrons will go here and will be extra electrons which do not fit into crystalline structure so all these electrons which don't fit crystalline structure are potentially migrants to fill up the holes here but as soon as they do this plus again will attract them and they will go again to the positive electron and this process will continue this will supply new electrons to the n-type these will be migrating into the p-type to fill up the holes and this positive charge will attract them even further again leaving the holes bare again which will be substituted with new electrons so the electrons will move all the time from negative to the positive and the current in the opposite direction is what if we will do a completely opposite sync but this is minus and this is plus well if this is minus these will not attract will not be attracted so they will remain in the covalent bond structure so they might actually be kind of pushed back since it's the negative right then this is negative there is a force which pushes back but again it it's not strong enough to basically push it across the border because there is no covalent bonds here ready for them to be kept you see when electrons moved there there are additional forces both to fill up the covalent bonds and attraction of the plus but if electrons move move here there is no covalent bonds which are ready to grab these electrons and the force of repelling is not sufficient to move electrons here so that's why it's semiconductor it's all depends on the level of voltage level of density of impurities in both sides etc but definitely under certain circumstances we can think about it but this force is not enough to move actually a lot of electrons back here because there is no covalent bond available for them which means that these negative electrons which are in the borderline after their migration so it's neutral but it's the covalent bonds are filled but electrons are still here there are no holes here well they will just stay there and they will prevent any other electrons to go this way or that way and the covalent bonds here are strong enough to resist the attraction of this plus so that's exactly where we have to really have some kind of a very finely calculated voltage against the covalent bonds obviously if I will put a very strong minus and very strong plus I will just rip off all the electrons all the valence electrons from everywhere everywhere so we're not talking about this that's not interesting what's interesting is to have certain density of impurities in both cases and certain voltage and it's all calculated in such a way that this particular device which is called a p-n junction diode will only conduct electricity when electrons are moving this way and not that way that's basically how our diode is arranged this is the p-n junction diodes that make basic principle so again what's important is that it works only if there is certain finely calculated balance between intensity of the applied voltage in both sides and certain density of impurities which we introduce into n-type and p-type if it's all done correctly and obviously by now we have a very good experience how to do it correctly we will have this diode working for certain particular voltage so obviously it's low voltage all our computers are basically low voltage computers and semiconductors basically help in this particular case because it's exactly this range of voltages where they work now we are not talking about technology of how to introduce these impurities how to make this junction etc it's all technological thing which not subject of this course at all we are talking about principle and the principle is the covalent bonds are strong the electrostatic attraction and repelling are strong and they are supposed to work in conjunction which with with each other and that's how the whole thing is made I suggest you to read the notes for this lecture on junisor.com you go to physics 14 course electromagnetism and then there is a in a semiconductor part there is a lecture about electronics related to semiconductors well that's it for today thank you very much and good luck