3a. (i) Measure and record the e.m.f of the accumulator provided.

(ii) Connect the circuit as shown in the diagram. S is a standard resistor, and R is a resistance box.

(iii) With R = 0 Ω, close the key K. Read and record the ammeter reading I. Evaluate I\(^{-1}\).

(iv) Repeat the procedure for R = 1, 2, 3, 4, and 5 Ω. Tabulate your readings.

(v) Plot a graph of R on the vertical axis and I\(^{-1}\) on the horizontal axis, starting both axes from the origin (0,0).

(vi) Determine the slope s of the graph and find the intercept c on the vertical axis.

(vii) State two precautions taken to ensure accurate results. [21 marks]

bi. State two advantages of a lead-acid accumulator over a Leclanche cell. [2 marks]

ii. A parallel combination of 3 Ω and 4 Ω resistors is connected in series with a resistor of 4 Ω and a battery of negligible internal resistance. Calculate the effective resistance in the circuit. [2 marks]