You are provided with a constantan wire, a 2\(\Omega\) standard resistor, an accumulator E, an ammeter A, a key K, and other necessary apparatus.

1. Measure and record the e.m.f.of the accumulator provided.
2. Connect a circuit as shown in the diagram above.
3. Close the key, read and record the ammeter reading l\(_{o}\) when the crocodile clip is not in contact with the constantan wire.
4. Open the key. With the clip making contact with the wire, when I = 90cm, close the key. Read and record the ammeter reading /. Evaluate l\(^{-1}\).
5. Repeat the procedure for l= 80, 70, 60 and 50cm.
6. In each case, read and record the ammeter reading and evaluate l\(^{-1}\). Tabulate your readings.
7. Plot a graph of l on the vertical axis against l\(^{-1}\) on the horizontal axis.
8. Determine the slope, s, of the graph and its intercept, c on the vertical axis.
9. Evaluate k = \(\frac{c}{s}\).
10. Using your graph, determine the Current i when / = 55cm.
11. State two precautions taken to ensure accurate results.

(b)i. Explain what is meant by the potential difference between two points in an electric circuit.

ii. State two factors on which the resistance of a resistance wire depends.