Fig. 8.1 illustrates a 12.0 V power supply in a circuit that contains a lamp and a resistance wire AB of constant cross-sectional area. A sliding contact can be shifted to any point between A and B.
(a(i))[2]
Calculate the current flowing in the lamp when it is at normal brightness.
(a(ii))[2]
Calculate the resistance of the lamp when it is at normal brightness.
(b(i))[1]
Explain, without calculation, why the lamp becomes dimmer.
(b(ii))[3]
Calculate the distance AX needed for the lamp to be at normal brightness.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “A correct rearrangement of $P = VI$ OR $I = P / V$” …