Experiment to find how the Length of the Wire affects the Resistance of the Circuit.

Authors Avatar

Experiment to find how the Length of the Wire affects the Resistance of the Circuit

Aim

To see how the length of the wire affects its resistance while in a circuit.

Hypothesis

I predict that as the length of the wire increases so will the resistance, proportionally, so the graph should be a relatively straight constant line.

I believe that the resistance of the wire is proportional to the length of the wire, the scientific theory is based on is ohm’s law, which states:

For a given conductor at a constant temperature the current is proportional to the applied voltage.    

This shows that the equation for resistance is I = V/R where R is constant, this can be rearranged to R = V/I where I is constant, this will be the equation used to work out the resistance in the wire.

Current is the flow of electrons in a circuit and resistance is the resistance to those electrons that are trying to get through the circuit. The harder it is for the electrons to get through the circuit, the high the resistance is. The thing in the conductor that resists the current going through it easily is the atoms in the conductor.

    

If the wire is longer then there are more atoms to knock pass so there is more resistance against the electrons going through the wire. Therefore the resistance of the wire increases as the length does.

Method

 

I will set up a circuit with an ammeter and a voltmeter, keeping the current constant and measuring the voltage of the wire, we can work out the resistance as the length increases. The circuit was set up like below.

     

I will use the variable resistor to keep the current at 0.5 A because every time the length of the wire is increased the current has to be changed to 0.5 A. I have kept the current constant for the ease of the calculations when working out the resistance.

Join now!

I am going to measure the voltage of the wire as the length is varied. The lengths of the wire that voltage will be measured at are from 10cm to 100cm with the wire changing length by 10cm every time e.g. 10cm, 20cm, 30cm etc.

A 100cm piece of 32-gauge wire will be laid out on a ruler and the crocodile clips will be attached to the wire while laid out on the ruler so that I don’t have to cut separate pieces of wire for every variation of length in the wire.

   

Fair Test

The ...

This is a preview of the whole essay