gcse physics coursework resistance of a wire conclusion

In this investigation I am going to investigate what affect the resistance of a wire. Electricity flows in metals. Metal wires are made of millions of tiny metal crystals. Each crystal’s atoms are arranged in a regular pattern. The metal is full of ‘free’ electrons that do not stick to any particular atom. They fill the space between atoms in a metal. When these electrons move they create an electric current. Conductors have resistance, but some are worse than others. The free electrons keep bumping into atoms. A wires resistance depends on four main factors which are: Resistivity The length of the wire Cross sectional area The temperature of the wire I am going to investigate how the length of the wire affects the resistance. I have done a preliminary experiment to help me decide the best way to do my investigation. The results should also help me make a prediction. New Beats by Dr. Dre Solo2 Headband Headphones Gloss Grey Below are my results from the preliminary experiment (see table 1). I have taken three readings each from the Volts and current to make sure it is as accurate as possible See all 5 photos From the results I can see that as the length of the wire increases, the resistance increases as well. Furthermore I have noticed that if you double the length of the wire, the resistance is roughly doubled. E.g. when the length of the wire is 20cm the resistance is 3.14 ohms, when the length of the wire is 40cm the resistance is 6.18 ohms which is roughly double 3.14 ohms. In my main investigation I will see if this theory applies to my results. I found that the apparatus I used was suitable but I think that I could possibly increase the range of my results to obtain very reliable results, perhaps maybe increasing the length of the wire by 5cm each time instead of 10cm. Aim I am going to investigate the resistance of a wire in relation to its length. Prediction.
Extracts from this document. An experiment to find the resistivity of nichrome A. Planning Plan of the method to be used: - The resistivity of nichrome can be determined using the equation ??=?RA/L Where: R:- Is the resistance of the wire in ? ohms and can be determined using the equation R=V/I where V is voltage in volts and I is current in Amperes. L:- Is the length of the nichrome wire used in metres. A:- Is the cross-sectional area of the wire in metres square and can be determined using the equation A= ??d2 where d is the diameter of the wire. If I plot a graph of length on the x-axis against resistance on the y-axis. From the relation R = ? L /A which corresponds to the st. line equation ? y=mx the graph should be a st. line passing through the origin where m is the gradient of the st. line graph and corresponds to ?/A. Since the cross-sectional area of the wire can be found by knowing it's diameter. Therefore the resistivity of nichrome can be calculated. ? Diagram of the circuit used in this experiment List of the apparatus used: - 1- Power pack supply of 4V 2-A variable resistor 3-A full scale deflection ammeter with a measuring range of 0-1 A 4-A digital voltmeter with a measuring range of 0-5 V 5-P, Q represents terminal blocks. 6-Circuit wires 7-PQ=Nichrome wire 8-A meter ruler 9-Michrometer screw-gauge 10-Sellotape Detailed method: - I set up the circuit as shown in the diagram that I have drawn. I started the experiment by taping a meter ruler between the terminal blocks P, Q so that I could measure 100cm of nichrome wire. I made sure that the wire was carefully tightened at both terminals to try to minimise the kinks or twists in the wire. I then switched on the power pack supply and adjusted the variable resistor until a constant current of 0.2A was flowing through the circuit.read more. 5 10 15 20 25 30 35 40 45 50 This will investigate the value.