Investigating how thickness and length affect the resistance of a wire.

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Investigating how thickness and length

Affect the resistance of a wire

Introduction

 I plan to investigate how the length and thickness of a wire affects the resistance.  I plan to do this by keeping the voltage the same by using a variable resistor and measure the current when varied lengths and thicknesses of wire is in a circuit

Variables

 There are a few factors that can affect the resistance.  These are;

        Temperature

        Thickness

        Length

        Material

        I plan to change the length of nichrome wire at intervals of 10cm’s.  I also plan to investigate how the thickness of a wire affects the resistance.  I plan to do this by measuring different lengths and both thicknesses of wire and comparing results.  In my experiment, the voltage, material and temperature will remain constant.

Prediction

        I predict that the longer the wire is the more resistance there will be.  In relation to the thickness, I predict that the thicker nichrome wire will produce less resistance.  I assume that as the length of the wire doubles the resistance will also, therefore the current halves, this means I think that resistance is proportional to length and will show a straight line on a graph.

        I predicted that the resistance decreases as the wire increases in thickness.  I will be using a wire that is double the thickness of the previous one, therefore has double the cross-sectional area.  I believe that the current will increase as the thickness of wire increases, this is because when the cross-section increases the amount of electrons also increases, which therefore increases the amount of charge being carried.

Preliminary work

        To ensure that my experiment will be a success I plan to do some preliminary work. To determine whether the different lengths of nichrome wire is suitable, I plan to take a readings at 10cm and at 80cm.  If the current reading has a suitable difference I shall carry on with the experiment.  If the readings are too close then I will have to carry out more preliminary work until I find suitable readings.

Safety

        Although this investigation is fairly simple and not particularly dangerous, there are some safety precautions that need to be taken into consideration;

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        Temperature of wire, as more voltage continuously flows through wires, it’s possible and very likely that they may heat up.  To prevent this, use a switch or simple disconnect the circuit when not in use, this stops the voltage flowing and therefore is less likely for the wire to get hot.

        It is possible for a wire to suddenly snap and may come up, although this is very unlikely, it’s best to stay aware of this factor and wear goggles.

Fair Test

        In every investigation it’s important to perform a fair test, if an investigation / experiment is ...

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