A $12\,\text{V}$ battery is connected in series with a $24\,\text{W}$ lamp and a parallel arrangement of identical resistors X and Y. Fig. 9.1 shows the circuit diagram. The $24\,\text{W}$ lamp glows at normal brightness when the potential difference (p.d.) across it is $6.0\,\text{V}$.
(a)[3]
Calculate the lamp’s resistance.
(b(i))[1]
Determine the p.d. across A and B.
(b(ii))[1]
Determine the combined resistance of the parallel pair formed by identical resistors X and Y.
(b(iii))[2]
Determine X’s resistance.
(c)[2]
Explain why the lamp is dimmer.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “I = P/V, or R = V/I” …