Investigation of how the Length of Wire affects its Resistance.

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        Jamie Willis        

Investigation of how the Length of Wire affects its Resistance

Planning

Prediction

I expect that the longer the wire is the higher the resistance will be. I predict this because in our preliminary experiment the length of wire affected the resistance. We discovered the longer the wire the further the current needs to travel and this cause’s higher resistance. This is because of the more atoms the current needs to pass. With there being more atoms there are many collisions and this is the source of resistance over length.

Equipment

  • Resistance Board
  • Power Supply (4V)
  • Ammeter (2A)
  • Voltmeter (6V)
  • 5 constantan wires

Method

I will create a circuit as seen here containing a resistance board, four volt power supply, ammeter and voltmeter. Next I’ll measure out points along the Resistance Board at 5cm intervals, connect one lead to one lead of the board and the other at the first 5cm interval. I’ll make a record of the readings from the ammeter and voltmeter and with this information work out the resistance using this equation:

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Resistance (Ω) = Voltage (V) / Current (A) or R=V/I

I’ll move the lead up to the next interval, the 10cm marker and record and work out the results from that. I’ll continue this until I have results for all 10 intervals.

To make sure that my investigation is safe I will stick to the 4v limit and not use anything higher. Also I’ll be careful when putting a current through the shorter intervals. The resistance can be so low here that the wire heats up and can snap.

I’ll make sure that I keep the investigation fair ...

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