Physics 5054 · O Level · Series and parallel circuits
Series and parallel circuits — practice question
A circuit containing an ammeter, a light-dependent resistor (LDR) and a 1800 Ω fixed resistor is powered by a 4.5 V battery. Fig. 7.1 shows the circuit diagram.
(a(i))[2]
The LDR has a resistance of 9000 Ω. Calculate the overall resistance of the circuit.
(a(ii))[2]
Calculate the ammeter reading.
(b(i))[1]
A very bright lamp is switched on so the light intensity falling on the LDR rises. State and explain what happens to the current in the LDR.
(b(ii))[1]
State and explain how the current in the 1800 Ω resistor changes.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “1/R = 1/R1 + 1/R2 = 1/1800 + 1/9000” …