Physics 9702 · AS & A Level · Rectification and smoothing

Rectification and smoothing — practice question

Fig. 5.1 shows part of an electric circuit. The circuit is intended to give half-wave rectification of an alternating voltage with potential difference (p.d.) $V_{\text{IN}}$. The p.d. across the $14\,\text{k}\Omega$ resistor at the output is $V_{\text{OUT}}$.
(a(i))[1]

A component is absent from the circuit in Fig. 5.1. Complete Fig. 5.1 by inserting the circuit symbol for the missing component in the correct position.

(a(ii))[1]

A capacitor $C$ is included in the circuit of Fig. 5.1. State the effect on $V_{\text{OUT}}$ when the capacitor is added to the circuit.

(b)

Fig. 5.2 plots $V_{\text{IN}}$ against time $t$.

(b(i))[1]

Determine the frequency corresponding to $V_{\text{IN}}$.

(b(ii))[2]

Show that the time constant $\tau$ for discharge of the capacitor through the resistor is $0.038\,\text{s}$.

(b(iii))[2]

Calculate the capacitance of $C$ and include a unit in your answer.

(c)[2]

The circuit in Fig. 5.1 is changed so that it gives full-wave rectification of an input voltage. Suggest, with a reason, how $V_{\text{OUT}}$ now changes with time when $V_{\text{IN}}$ is as shown in Fig. 5.2.

(c(i))[1]

Determine the frequency of $V_{\text{IN}}$.

(c(ii))[2]

Show that the time constant $\tau$ for discharge of the capacitor through the resistor is $0.038\,\text{s}$.

(c(iii))[2]

Calculate the capacitance of $C$ and state a unit in your answer.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: Diode symbol correctly inserted in series.

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