A student investigates the resistance of a resistance wire. The circuit used is shown in Fig. 2.1. [Figure 2.1] The crocodile clip attached to the flying lead is connected to different points along the length of the resistance wire.

1. (a)(i)Fig. 2.2 shows the voltmeter when the flying lead is connected to the resistance wire at the 100.0 cm mark on the rule and the switch closed. [Figure 2.2] Read the voltage shown in Fig. 2.2 and record the reading in Table 2.1 on page 6.[1]
2. (a)(ii)Calculate the current I for each length L shown in Table 2.1 using the equation I = V/10. Record your answers in Table 2.1. Calculate values of 1/I for each length L shown in Table 2.1 and record your answers in Table 2.1. Write the units in the top row of the table.[3]
3. (b)(i)On the grid on page 7, plot a graph of 1/I on the y-axis against L on the x-axis. Start both axes at the origin (0,0).[2]
4. (b)(ii)Draw the straight line of best fit. Extend this line to intercept the y-axis.[1]
5. (b)(iii)Determine the gradient G and y-intercept c of this line. Show clearly on the graph the values you choose and show your working.[2]
6. (c)Theory suggests that: RW = 1000 G / C where RW is the resistance of the wire. Use your answers in (b)(iii) to determine RW. Show your working.[1]

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