# To investigate how the piece of resistance wire depends on length and to find the length of wire needed to make the required resistors

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Introduction

Aim: To investigate how the piece of resistance wire depends on length and to find the length of wire needed to make the required resistors

Introduction:

The purpose of this investigation is to find out whether the length of a resistance wire affects the resistance. Resistance is the name given to a material that resists the flow of electrical current and is measured in ohms (Ω). I am going to carry out an experiment that will allow me to see the effect on the wire’s resistance through how long the wire is. Hopefully, this experiment will lead to a conclusion reflecting the statements made in my prediction.

Prediction:

I predict that the longer the wire will be, the higher the resistance will be.

Middle

The diagram above shows that when electrons are travelling through a long wire, they have a larger length to travel. They will also have to manoeuvre past more ions, making the risk of collisions more likely.

I believe that at a length of 20cm, the resistance will be close to 2 Ω and at 50cm, the resistance will be just over 3 Ω and finally at 100cm, the resistance will be 7 Ω. They wouldn’t collide as much in a shorter wire than in a longer wire because of this piece of information. Resistance should also be proportional to the length of the wires, so if you double the length, the resistance will also double.

Apparatus:

-Leads

-Ammeter (of scale 0amps to 1amp – this is because of the results from my preliminary work, which showed that most results came in and around this scale, and so it would make my results more accurate if I used this sort of scale)

-Voltmeter (of scale 1V to 6V)

-D.C. Power Supply

-Ruler (1m)

-Cello tape (To keep the wire as straight as possible. I found out that in my preliminary work, the wire barely stays straight and it is very difficult to restrain it.)

-Constantan Wire – 30 SWG (I have chosen to use constantan wire because its temperature stays fairly constant when a current/voltage flows through it)

-Micrometer

-Crocodile Clips (X2)

Circuit diagram:

Method:

Conclusion

This same experiment could also be carried out using a different method; instead of using an ammeter and a voltmeter, an ohmmeter could be used, which would drastically improve the accuracy of my results even more. This is because I wouldn’t have any chances of making any human errors while reading the meters or while calculating the resistance.

The diameter of my wire was roughly the same at all positions. I know this because I used a micrometer to measure the diameter of my wire at 3 positions and the readings I got were, 0.315mm, 0.31mm and 0.31mm This meant that my test would be fair because if the wire was maybe thicker, then the resistance would be less due to the fact that the electrons will have a greater diameter in which to not collide with the ions.

Conclusion:

To conclude, I have proved that the longer the length of a resistance wire is, the larger the resistance is. I have done this using a wide array of equipment, my own knowledge and the formula for working out resistance. To show that I have proven this statement, I have drawn a graph that clearly shows this through the line of best fit.

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

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