Investigate how the resistance of a wire changes due to different factors experimented on it.

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PHYSICS COURSE WORK

PLAN

Aim

Investigate how the resistance of a wire changes due to different factors experimented on it.

Factors

Factor 1 – The length of the wire may affect the wire’s resistance. According to the length of the wire, current, voltage and resistance may change. For example it may occur that the shorter the length of the wire, the higher the voltage and the lower the current meaning that resistance of the wire should increase.

Factor 2 – The type of wire may affect the wire’s resistance. For example if the wire is copper then it may occur in the experiment that the resistance may decrease due to the fact the current is higher then it would be in a different type of wire.

Factor 3 – The thickness of the wire may have an affect on the wire’s resistance. It may occur that the resistance decreases because the wire is thin or that when the wire is at its thickest the resistance will be at its highest.

Factor 4 – The temperature applied on a wire may have an affect on its resistance. For example it may mean at a higher temperature there might be more voltage applied across the wire meaning there will be more resistance.

I have chosen to investigate the length of the wire.

Prediction

I predict that the longer the length of the wire, the higher its resistance. I predict this because using my preliminary results and ‘Ohms Law’ we know that as the distance between the ends of the conductor increases, the resistance will also increase. Therefore using this I know that when the length of the conductor is at its longest its resistance will also be at its highest.

Also, as the wire length increases, it will mean that free electrons will have to travel further than it needed to before in the wire. This means the free electrons will loose some of their charge. As a result the current will decrease, therefore making the resistance in the wire increase. This is because, when the wire length is longer there are more atoms and impurities in the metal wire, which means that more free electrons will collide with the atoms and impurities and more energy will be lost, therefore the resistance of the metal wire will increase. So if the length of the wire were at its longest the amount of atoms and impurities in the metal wire will increase, which will mean there is more chance of free electrons colliding into them. This will cause more energy to be lost in the form of heat meaning the resistance of the wire will increase even more.

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The diagram on the next page will show this more clearly:

½ of length of wire

+    E        +          +        +   E        +  E        +

+        E       +          E     +          +         +            E

Double the length of the wire

        +        +           E          +   +             +               +            E     +         +     ...

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