You are provided with a potentiometer AB, a 102\(\Omega\) standard resistor R, a battery of emf 4.5V, a jockey J, and other necessary materials.

1. Connect a circuit as shown in the diagram above.
2. Close key K. Without J making contact with AB, read and record the ammeter reading I. Open the key.
3. Use the jockey to make contact with AB at the 20cm mark such that AJ = x = 20cm. Close the key, read and record the ammeter reading.
4.  Evaluate x\(^{-1}\).
5. Repeat the procedure for values of x= 35cm, 45cm, 60cm, and 80cm respectively.
6. Tabulate your readings.
7. Plot a graph with x\(^{-1}\) on the vertical axis and l\(_{i}\) on the horizontal axis, starting both axes from the origin (0, 0).
8. Determine the slope, s, of the graph.
9. From your graph, determine the value l\(_{o}\) of I\(_{1}\) for which x\(^{-1}\)= 0.
10. Evaluate \(\frac{I_{o}}{I}\).
11. State two precautions taken to obtain accurate results.

(b)i. Define the emf of a battery.

ii. A cell X of emf 1.018V is balanced by a length of 50.0cm on a potentiometer wire. Another cell Y is balanced by a length of 75.0cm on the same wire. Calculate the emf of Y.