Question

How can capacitor filter out the ac ripple and give a pure dc Voltage?? or what is the role of capacitor in filtering in a rectifier?

Answer 1

Since capacitor blocks DC and let the AC passes by we can filter out pure DC voltage.

Capacitive reactance Is given by

Xc = 1/2лfc

now for DC f= 0. As a result of which a capacitor offers infinite resistance to the DC voltage. Thus DC does not pass through it while AC does as it has some finite frequency. So, DC is filtered out.