A 12V battery is connected to a 4Ω resistor. The following measuring instruments are available in the laboratory:
Ammeter P : 0–250 mA
Ammeter Q : 0–5 A
Voltmeter R : 0–5 V
Voltmeter S : 0–15 V
(i) Calculate the current through the resistor and the potential difference across it when the circuit is operating normally.
(ii) From the instruments listed, choose the most suitable ammeter and voltmeter to measure these quantities. Give reasons for your choice.
(iii) If Ammeter P were used instead of your chosen ammeter, predict what would happen to the meter and to the circuit. Give a brief explanation.