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Physics practical

Resistance of a wire and its length

Slide a clip along a resistance wire, read the voltmeter and ammeter at six lengths, and show that resistance is proportional to length.

What you will do

  1. 01Put the flying clip on the wire and read its length on the metre rule.
  2. 02Close the switch, read the voltmeter and the ammeter at once, and open the switch again.
  3. 03Repeat for at least five lengths from about 20 cm to 100 cm.
  4. 04Calculate R = V / I for each length.
  5. 05Plot R against length, draw the best straight line, and find its gradient.