A student sets up the circuit shown in Fig. 5.1 to measure the resistance of a length of wire. The circuit contains four identical cells. A V length of wire [Figure 5.1] The student finds that both meters read zero when the switch is closed. This is because the circuit shown in Fig. 5.1 is not suitable for the measurement.

1. (a)Describe all the changes to the circuit in Fig. 5.1 that are needed so that the meters produce readings that can be used to calculate the resistance of the length of wire.[2]
2. (b)(i)Fig. 5.2 shows the current-voltage graph for a 9.0 cm length of wire (line P) and for a different length of the same wire with the same cross-sectional area (line Q). 0.8 0.6 current/A 0.4 0.2 line Q line P 9.0 cm wire 0 0 1 2 3 4 5 6 voltage/V [Figure 5.2] Calculate the resistance of the 9.0 cm length of wire. resistance = ....................................................Ω[2]
3. (b)(ii)Explain whether line Q is obtained with a length of wire that is longer or shorter than 9.0 cm.[1]
4. (b)(iii)Calculate the length of the wire used to obtain line Q. length = ....................................................cm[1]

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