Investigate how the length of wire in a circuit, the type of metal used and the width of the wire affects the resistance of the circuit.

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Stefan Piatek

Introduction:

In this piece of work I will investigate how the length of wire in a circuit, the type of metal used and the width of the wire affects the resistance of the circuit.

Prediction:

I know that as you increase the length of a wire, the resistance increases, (directly proportional) I know that if you make the wire thinner the resistance should increase as well (inversely proportional) This is because in a thicker wire there are more electrons to travel through the wire, which would increase the current, and decrease the voltage since V=IR, or R=V/I if the current goes up and the voltage goes down, the resistance must go down. No two different metals will have the same resistance so one of them will have more resistance than the other .I am expecting to find; the longer the wire, the higher the resistance, the thinner the wire the higher the resistance and one of the wires to definitely have more resistance than the other

Apparatus:

Ammeter

Voltmeter

A power pack

Crocodile clips

Wire connectors

Variable resistor

1m of 28 SWG Maganin

1m of 28 SWG NiChrome

1m of 30 SWG NiChrome

Method:

Warning: Electrical equipment in use, wire can get hot, be cautious

  1. Set up a circuit as shown
  2. Measure out every 5 cm on each wire
  3. Attach crocodile clips to one end of the Maganin wire and another at the 5 cm marker
  4. Turn on power supply and copy down the Volts and Amps shown
  5. Repeat this 3 times (for reliable results)
  6. Repeat numbers 3.4.5., moving up 5 cm each time until the length is 1m
  7. Attach crocodile clips to one end of the NiChrome 28 SWG wire and another at the 5 cm marker
  8. Turn on power supply and copy down the Volts and Amps shown
  9. Repeat this 3 times (for reliable results)
  10. Repeat 7. 8. 9. moving up 5 cm each time until the length is 1m
  11. Attach crocodile clips to one end of the NiChrome 30 SWG wire and another at the 5 cm marker
  12. Turn on power supply and copy down the Volts and Amps shown
  13. Repeat this 3 times (for reliable results)
  14. Repeat 11. 12. 13 moving up 5 cm each time until the length is 1m
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In this experiment there are certain factors that will affect the accuracy of results, they are:

Temperature of the circuit, time taken to take measurement of voltage and amps, and length of the wire, type of wire, thickness of the wire. I will make sure, that out of these, I will keep the temperature of the circuit (do this in the same room, and since there is central heating, there should be a constant temperature), the time taken to take the measurements constant. The length of the wire, type of wire, and thickness of the wire are variable ...

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