Physics 9702 · AS & A Level · Rectification and smoothing

Rectification and smoothing — practice question

Fig. 5.1 displays four diodes together with a load resistor of resistance $1.2\,\text{k}\Omega$, arranged in a circuit used to rectify an alternating voltage.
(a(i))[1]

State the meaning of rectification.

(a(ii))[1]

State the type of rectification produced by the circuit in Fig. 5.1.

(b(i))[1]

A sinusoidal alternating voltage $V_{\text{IN}}$ is applied between input terminals X and Y. The change with time $t$ of $V_{\text{IN}}$ is described by $V_{\text{IN}} = 6.0 \sin 25\pi t$, where $V_{\text{IN}}$ is in volts and $t$ is in seconds. On Fig. 5.1, mark output terminals P and Q with the correct symbols to show the polarity of the output voltage $V_{\text{OUT}}$.

(b(ii))[3]

The size of the output voltage $V_{\text{OUT}}$ changes with $t$ as shown in Fig. 5.2. On Fig. 5.2, label both axes with the correct scales. Use the space below for any calculations you need.

(c(i))[1]

The output voltage in (b) is smoothed by placing a capacitor in the circuit in Fig. 5.1. The difference between the largest and smallest values of the smoothed output voltage is $10\%$ of the peak voltage. On Fig. 5.1, draw the circuit symbol for a capacitor to show that it is correctly connected in the circuit.

(c(ii))[2]

On Fig. 5.2, sketch how the smoothed output voltage varies with $t$.

(c(iii))[3]

Calculate the capacitance $C$ of the capacitor.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: Changing from a.c. to d.c.

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