(a)(i) Describe, with the aid of a circuit diagram, an experiment to measure the resistance of a wire given an ammeter of low resistance, a battery, a key, ...

(a)(i) Describe, with the aid of a circuit diagram, an experiment to measure the resistance of a wire given an ammeter of low resistance, a battery, a key, a rheostat, va high-resistance voltmeter and some connecting wires.

(ii) State two precautions necessary to obtain an accurate result.

(b) Using the experimental result and any necessary measurements, explain how the resistivity of the wire may be determined.

(c) Two cells, each of e.m.f. 2V and internal resistance 0.552, are connected in series. They are made to supply current to a combination of three resistors, one of resistance 20 connected in series to a parallel combination of two other resistors each of resistance 3Q. Draw the circuit diagram and calculate the:

(i) current in the circuit

(ii) potential difference across the parallel combination of the resistors

(iii) lost volts of the battery.