How does the length of wire affect its resistance...?

Aim:

Conduct an experiment to investigate how changing the length of a length of wire affects its resistance

Section 1… Planning (8 marks)

Method…

I will build the following circuit

Theory…

There are four things that affect the resistance of a piece of wire

In this experiment I will change the length, whilst keeping the other factors (area, temperature and material) constant

I will also keep the wire straight to make the length measurement more accurate

Prediction…

An electric current is a flow of electrons along a length of wire.

The electrons have a negative charge, these move past ions which have a positive charge.

There is an attractive force between the charges and ions, so they tend to stop flowing, so energy has to be supplied to keep the electrons flowing

The longer the piece of wire the greater the resistance, because the electrons have got to push past more ions.

So… If the length of wire increases the resistance will also increase

Keeping other Factors constant…

Temperature…

If the temperature increases, the ions will vibrate more. The electrons will find it harder to get past ‘vibrating atoms’. This will increase the resistance.
High currents in wires heat them up, therefore increasing the resistance.
So to keep the temperature low, I will use a low voltage (1.5V) to keep the current low.

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