Investigation into the relationship of the length of wire and the resistance.

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Thomas Hone                                                                              20/01/04

Investigation into the relationship of the length

of wire and the resistance

How does the length of wire affect the resistance?

Planning

Prediction: I think that the longer the piece of wire, the more resistance will be created. I think this because in a circuit electrons move around it creating electricity in the wires. If there is more length of wire there will be then more wire atoms in the way of the electrons moving round the circuit:

   - Wire Atom                        

   - Electron        

                

Small piece of Wire: There some atoms in

way of the electrons moving.

Long piece of wire: There are a lot more wire atoms in the way of electrons.

Resistance is caused when electrons collide with atoms. Because there is a lot more wire atoms in the way of the electrons, the electrons must collide more, so slow down. E.g. if you are travelling down a road and there are a few of parked cars, it will take you a while to get through, but if you are travelling down a longer piece of road and there are more parked cars it will take you much longer.

As the electrons slow, thus the current, (current = how fast the flow of electrons is) slows down.

Preliminary Work: We started our preliminary work to find out these things:

  • The smallest piece of wire that could be used without it getting hot.
  • The largest piece of wire we could get or use.
  • What would be a reasonable voltage to keep the same.

We first started the preliminary work with the circuit we would use in the main test:

                                                                                     - Voltmeter

                                                                                                                                                                      - Wire

                                                                                                                                                                  - Power supply

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We did some tests with different voltages and sizes of wire. We first chose to have the smallest wire we would use as 10cm. We will them increase the size of wire up by 10cm each time until 100cm. We chose that because it is and easy length to use and it can be easily measured.

        We then did more test with the 10cm piece of wire to see what would be a suitable length that was not hot. We chose 0.9 volts because a 10cm piece of wire that was the maximum it could be before ...

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