Resistance RPA

Question 1

Method for using voltmeter and ammeter to calculate resistance with V=IR

Answer 1

1) attach the start of the resistance wire to the 0 mark on a metre ruler and then attach the ruler again 10cm along.
2) At these 2 points use crocodile clips to attach the wire to a circuit with an ammeter connected in series and a voltmeter connected in parallel
3) Turn on the power pack, measure current with ammeter and potential difference with voltmeter then turn it off
4) Move crocodile clip at 10cm along to 20cm and repeat step 3, increasing length of wire by 10cm each time up to 50cm
5) Record results on table and use formula V=IR to calculate resistance for each length
6) Plot graph showing resistance against length of wire

Question 2

Method 2 (using switch and variable resistor)

Answer 2

1) Attach one end of the resistance wire to the 0 mark on the ruler and then the next part 10cm along.
2) Use crocodile clips at these points to connect the wire to a circuit with a variable resistor, power pack, ammeter (all in series) and voltmeter (in parallel)
3) Turn on power supply, record current and potential difference then turn off
4) Repeat for different lengths of the wire by moving the crocodile clips up by 10cm each time
5) Calculate resistance using V=IR
4) plot results on graph