The wire showing its resistance Essay
The wire showing its resistance
I want to find out how the length of a wire changes the amount of voltage and current flowing though the wire showing its resistance. My prediction for the experiment is that as the length of the wire increases the resistance will also increase and as the wire decreases so will the resistance. I think this will happen because the loose electrons are being transported around the circuit and the wire will provide resistance to these, as it is like passing through a sponge rather than air. And so as there is more wire or sponge to pass through it will take increasingly longer and that is why I predicted that.
I will change the length of wire between 20cm and 100cm in intervals of 10cm each of these lengths I will do 3 times at different voltages, which are 0. 3v, 0. 6v and 0. 9v. I think this is important to ensure a reliable average. I will measure the amount of voltage and current passing through the circuit. I will keep the voltage the same through each set of experiments e. g. at 0. 3v I will make sure there is 0. 3v at 20cm and 0. 3v at 100cm by using a variable power pack. I will keep the same wires that link up the circuit so that they have the same resistance for each experiment.
I will keep the adjustable wire the same and use the same crocodile clips, voltmeter, ammeter and power pack to ensure a fair test. Doing a preliminary experiment helped me to decide what ammeter and voltmeter to use also what voltage to run through the circuit and how short the wire can get before overheating. It also helped me confirm my prediction. It helped me decide to use a digital voltmeter because it gave more accurate readings. The equiptment I will need Power Pack 5 wires Ammeter 1 metre of wire 2 crocodile clips Voltmeter Diagram Resutls Table and Graph.
Length of wire (cm) Ex 1 Current at 0. 3 volts ( ) Ex 2 Current at 0. 6 volts ( ) Ex 3 Current at 0. 9 volts ( ) Ex 1 Actual Voltage (v) Ex 2 Actual Voltage (v) Ex 3 Actual Voltage (v) Length of wire (cm) Ex 1 Current x Actual Voltage ( ) Ex 2 Current x Actual Voltage ( ) Ex 3 Current x Actual Voltage ( )
Conclusion I have found out that the longer a wire the more resistance in that circuit which is exactly the same as my prediction.
The trends and patterns are that the longer the wire the smaller the difference in current and resistance. As in experiment 1 the difference in resistance between 10cm and 20cm is 0. 16 but the difference between 90cm and 100cm is just 0. 01. The reason we got these results is because the longer or larger a circuit that the current has to pass through the more resistance there is for the current because the wire provides resistance to the current and the more of that wire the current has to pass through the higher the resistance is going to be.
The results aren’t exactly what I predicted because I thought the graph would be a straight line and not curved, I don’t know why this is. Evaluation I think that the experiment went very well and I got the results I predicted and did not have any odd results. My method was probably the best method for carrying out this experiment. I could improve it though by doing each experiment more times and at smaller intervals of wire size e. g. every 5cm.
I could make the results more accurate by making sure the voltage was exactly what is meant to be e. g. 0. 6v not 0.605v. I think I have enough data to support my conclusion and the results are reliable however I could make them more reliable by doing each experiment more times. I think to provide more evidence for my idea by doing wires with different widths or thickness to prove that the more for the current to pass through the more the resistance.
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University/College: University of Chicago
Type of paper: Thesis/Dissertation Chapter
Date: 13 October 2017