Investigate how changing the length of a piece of wire affects its resistance.

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Chris Caulfield – 11K1                                                25th October 2003

Wire Resistance Investigation

Aim:        To investigate how changing the length of a piece of wire affects its resistance.

Prediction:        I already know that a short piece of wire has fewer atoms for the electrons to flow through, using the domino effect.  This causes there to be less resistance in the circuit.    This means that as the length of the wire gets longer the resistance in the circuit increases.

I predict that the longer the wire the higher the resistance.  This is because the electrons go slower because they meet more atoms.  Therefore the lower the current the higher the resistance.  

Equipment:        This is the apparatus I will use for my experiment:

  • Two batteries
  • Connecting wires
  • Volt meter
  • Ammeter
  • Heat proof mat
  • Wire
  • Crocodile clips

Diagram:

Plan:        We will be testing 5 different lengths of wire (20 cm, 30 cm, 40 cm, 50 cm and 60 cm) to find how this affects the resistance.  To do this we will do the following:

  1. Set up all equipment (as seen in above diagram – an ammeter, a volt meter,
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2 batteries and cut a length of wire, at least 60 cm long)

  1. Attach one end of wire to the crocodile clip and using the meter ruler measure 60 cm and clip the second clip at this point on the wire.
  2. Put the voltage onto 2 volts on the voltmeter.
  3. Take the reading of the ammeter so the resistance can be found.
  4. Repeat this method three times for each length of wire so the average resistance can be worked out.
  5. Repeat this method for every length of wire.  We will start with 60 cm and work down to ...

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