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GCSE Physics Coursework Centre Number: 12736 Nower Hill High School P ;O ; A ;E ;SP&G Scenario: Investigate the things that affect the flow of electricity through a conductor. Plan Aim: In order for an electric circuit to work charge must flow throughout the circuit. This flow of electricity or charge is known as the current, and in my experiment I aim to investigate how the flow of current through a conductor is varied when altering variables. Background information: As I have explained the current is the flow of charge and is measured in amps, this tells us how much charge is flowing through any point in the circuit in one second. As charge is measured in coulombs, one ampere is when one coulomb of charge passes in one second. This charge flow, therefore an electric current flowing trough metal conductors is caused because of the flow of electrons. In an atom the electrons are arranged in shells. The electrons in the shells closest to the nucleus are held strongly. The further the shell is from the nucleus the weaker the electrons are held. Thus, the outermost shell holds the electrons held weakest. Metals only contain one or two electrons in the outermost shell of each atom, therefore these are lost easily. As these electrons are held so weakly to the nucleus, they can easily break free from the atom when a push is supplied by the voltage of the battery, they are therefore ��free�� electrons. Voltage is a measure of the amount of electromotive force, e.m.f (energy) needed to push each coulomb of charge. Therefore voltage is a measure of joules per coulomb. As the atoms have lost negatively charged electrons when they have been pushed, they now become positive ions due to the unbalanced charge. The atoms or ions (when electrons are lost) in metals are arranged in regular crystal patterns. ...read more.


In order to make the test fair I am going to keep the following variables constant so that my results are as accurate as possible. I have already stated that I will keep the type of wire (constantan) the same and although I have not decided on a particular diameter for the wire, it will be kept constant in order to ensure that the experiment I am conducting is fair. In addition I found that when altering different lengths of the wire (constantan, used as conductor), the potential difference (voltage) across the length of wire also changed. As I am measuring the relationship between the current and the length, in order to keep my test I had to keep this value constant. I did so by altering the voltage on the power pack, so that the potential difference across the wire was always kept constant, at 6v. A factor that will affect my results if not kept constant is the room temperature. As I have already explained this will affect the current of across the conductor, but due to limited resources I am unable to control this. In order to make my results more reliable and accurate, I am going to take three measurements for each result so that I am able to take an average. Additionally my measurements will be made more precise as I am using suitable and accurate instruments, such as the voltmeter and ammeter, accurate to 2 decimal places. To further increase the accuracy of my results I will use the apparatus precisely and properly by taking measurements carefully. I will use the apparatus appropriately by using techniques such as ensuring that the positive terminal of the ammeter and voltmeter is are always connected so that they are closer to the positive terminal of the power pack. I will use my equipment accurately by using techniques such as ensuring the ruler is always parallel to the wire when measuring its length and recording the voltage and current only when the voltmeter and ammeter display stable readings. ...read more.


A major limitation I have already discussed is that if the room temperature increased or decreased it would have affected my results, as this would have altered the resistance and therefore the current flowing through the conductor. However as I have not recorded the change in room temperature I am unable to say to what extent they affected my results. Another factor affecting the results is when the electrons transferred their energy to the ions; the ions vibrated causing the wires to heat up. This would have increased the resistance of the conductor. This would have made the test unfair, as the following results would have been affected by the heating affect of the previous ones. This would have affected my results to a large degree. Another factor to take into account is human error. Although I undertook procedures to keep this minimal this would have still been evident, such as in my measuring in the length of the wire. However, this would only affect my results slightly, because the affects of this are minimal. These factors, particularly the heating of the wires, are the likely cause of anomalous results. To improve these limitations in my method, I could improve it primarily be conducting the experiment in controlled temperature conditions. There is no practical method reducing the heating affect of collisions, but it could be prevented by waiting a few minutes until the equipment has cooled down and then continuing with experiment. This would produce more fair results, but it would be too time consuming. The best way to reduce human error is by using more advanced equipment, in order to measure the length of the wire. Another limitation in my conclusion is that it cannot be taken generally as I have only conducted the experiment using one type of conductor and one type of voltage- my aim was to see how the length affected the current flowing through a conductor in general. In order t make the conclusion more general, and provide further evidence for it I could do further experiments such as using different voltages and conductors. ...read more.

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