How the length and thickness of a wire affects its resistance.

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Adam Todd 10L

28th May 2004

How the length and thickness of a

wire affects its resistance

I will be looking at how the length and thickness of a wire can affect its resistance when a current is passed through it.

The variables which could affect the resistance level of the wire are the thickness, length and type of wire. This will then affect the temperature and resistance of the wire.

Of these I will investigate the length of the wire and how it affects the resistance overall. When I do the experiment I will keep the type and length of wire the same. Also I will keep the voltage the same. The variable that I will change is the thickness of the wire. I will then record the different resistances of the wires by plugging in ammeters and voltmeters, taking the results, and then calculate the resistance in ohms (Ω) using the formula Resistance=               .

        The difference in thickness will change the resistance because of the equations used to calculate resistance. I predict that more thickness will decrease the resistance because there is more room for the current to move through.

        The formula for resistance is so that as more resistors appear, the overall resistance goes down. The calculation is 1/R. This means that when more resistors are added into the circuit the total resistance of that circuit decreases. The analogy of this is people walking down a corridor, where the people are the electrons and the corridor is the wire. If there are more corridors (wires) then it is easier and quicker for the people (electrons) to move along.

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Method and Equipment:

        I will need for this experiment wire (either Copper, Nichrome or Constantan), a ruler, a power box, circuit wires, an ammeter, a voltmeter, and crocodile clips.

        First I will set up the circuit with the ammeter and voltmeter in it. The voltmeter must be in parallel with the circuit it is measuring, while the ammeter goes in series. I will leave to open connections in it with crocodile clips on to allow the circuit to connect to the different wire thicknesses. Then I will connect one of the wires to the two crocodile clips, then turn ...

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