The function of the filter capacitor in a rectifier circuit is to reduce

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ALP CBT 2 Electrician Previous Paper: Held on 23 Jan 2019 Shift 1

Answer 1

A capacitor is included in the rectifier circuit to act as a filter to reduce ripple voltage.
The important property of the capacitor is that it passes the AC signal but blocks the DC signal and hence capacitor is used in the rectifier circuit.

F2 J.P Madhu 13.03.20 D1

The reactance of the capacitor is \({X_C} = \frac{1}{{j\omega C}}\)

Where ω = angular frequency

C = Capacitance

For the DC signal, ω = 0, so that X_C is infinite (theoretically).

For the AC signal, let assume ω = ω₁. Now if ω₁ is large, then X_C will be small so that impedance will be low.

Hence AC signal will pass through the capacitor but it blocks the DC signal. So that it reduces the ripples in the rectifier circuit.