Based on the understanding operations of rectifies answer the questions Diodes can be used for rectifying on ac voltage (restricting the ac voltage to one direction) with the help of a capacitor or a suitable filter, a dc voltage ca be obtained.

Capacitor is used in the rectifier circuit because :

It eliminates ripples/Fluctuations and gives almost constant DC voltage output across the

The correct answer is option (3) : It eliminates ripples/Fluctuations and gives almost constant DC voltage output across the

In a rectifier capacitor is used as a filter which eliminates ripples and gives almost constant dc output.