# What effects the resistance of a piece of wire?

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Introduction

What effects the resistance of a piece of wire? I have been asked to find out what will effect the resistance of a piece of wire. There are a few variables that I could test: * The thickness of a piece of wire * The type of wire * The length of the wire * The temperature The variable I have chosen to use is the length of the wire. I predict that the resistance will be higher when the wire is longer, therefore if I doubled the length of the wire the resistance would also double. I predicted this because if the wire is doubled there would be twice as many ions and electrons in the wire, and when the power in the wire is switched on the ions and electrons collide with each other and release heat energy, which is the resistance. So, if I doubled the length of the wire from 4cm to 8cm there would be twice as many ions and electrons in the 8cm piece of wire than in the 4cm piece of wire meaning there would be twice as many collisions making twice as much resistance. ...read more.

Middle

3. Carry out the experiment with the current set between 0.1A to 0.3A. Place the different sized wires between the crocodile clips, switch on the current and take the voltage three times. Then work out the average voltage and use the equation: R=V/I R=resistance, V=voltage, I=current To work out the average resistance. Here is a table to show the results of my experiment: To do the experiment first I had to set up my equipment in the correct way then I measured the maximum length of wire, which was 100cm. Then I did the experiment by placing the wire in the crocodile clips and switching the power on. Before I took any readings I made sure that the current on the ammeter was at 0.2A as a safety precaution to make sure that the wire didn't get too hot and also to make the experiment a fair test. To adjust the current on the ammeter I had to adjust the variable resistor slightly. When everything was correct I took the voltage 3 times and worked out the average voltage. ...read more.

Conclusion

We overcame this problem by taking the wire out and putting it in the other way. My measurements are quite accurate because on the graph the results all line up, part from a few results at the top of the graph. This may be because I might have measured the wire slightly wrong so the wire would be a little bit longer or shorter than it should have been which would effect the amount of resistance produced. My prediction was that if I doubled the wire the resistance would also double. Because if the wire was double the length there would be twice as many ions and electrons, meaning that there would be two times as many collisions between the ions and electrons making twice as much resistance produced. My prediction was quite accurate I found this out because the result for a 5cm piece of wire is roughly half of the results for a 10cm piece of wire. The differences in the line of best fit may be due to incorrect measuring of ...read more.

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