Physics 9702 · AS & A Level · Rectification and smoothing

Rectification and smoothing — practice question

A sinusoidal alternating-voltage source is linked to a bridge rectifier made of four ideal diodes. The rectifier output is then connected to resistor $R$ and capacitor $C$, as shown in Fig. 6.1. The purpose of $C$ is to smooth the potential difference across $R$ to some extent. Figure 6.2 shows how the potential difference $V$ across resistor $R$ varies with time $t$.
(a(i))[1]

Use Fig. 6.2 to find the peak voltage for the alternating supply.

(a(ii))[1]

Use Fig. 6.2 to find the root-mean-square (r.m.s.) voltage of the alternating supply.

(a(iii))[2]

Use Fig. 6.2 to find the frequency of the alternating supply. Show your working.

(b(i))[1]

The capacitor $C$ has capacitance $5.0\,\mu\text{F}$. For one discharge of the capacitor through resistor $R$, use Fig. 6.2 to determine the change in potential difference.

(b(ii))[2]

Determine the change in charge for each plate of the capacitor.

(b(iii))[2]

Show that the average current in the resistor comes to $1.1 \times 10^{-3}\,\text{A}$.

(b)

The capacitor $C$ has capacitance $5.0\,\mu\text{F}$. For one discharge of the capacitor through resistor $R$, use Fig. 6.2 to answer the following.

(c)[2]

Use Fig. 6.2 together with the current value given in (b)(iii) to estimate the resistance of resistor R.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: $V_{\text{peak}}=4.0\,\text{V}$

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