An a.c. source of 200 V is connected through a diode 'D' to a capacitor as shown in figure. Find the maximum potential difference across the capacitor:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 283 V
The diode conducts only in the half-cycle in which it is forward biased, and it charges the capacitor up to the peak value of the source voltage. When the voltage then falls, the diode is reverse biased (an ideal diode takes no reverse current), so the capacitor cannot discharge and stays at the peak value.
A rated a.c. voltage such as 200 V is, by convention, the rms value, so the peak value is
\( V_0 = \sqrt{2}\,V_{\mathrm{rms}} = 1.414\times200\,\mathrm{V} \approx 283\,\mathrm{V} \)