Question

what is the use of ripple factor

Answer 1

The ripple factor has to do with the rectified output of a transformer, either half wave or full wave. With capacitance across load their will be a peak to peak value at the load known as ripple. There will be less ripple for full wave than half wave for the same load, also a frequency difference, 120 Hz, 60 Hz for normal US household. Depending of required ripple factor you chose half or full wave and the size of capacitor for particular load, for further decrease in ripple one may add a DC regulator circuit which may require a minimum ripple in.