The output obtained from a rectifier is the superposition of both ac & dc components. The ratio of ac component to the dc component in the rectified output is called the ripple factor it decides the effectiveness of a rectifier. i.e.
ac power input
It is the effective input power i.e.
dc power output
It is the effective output power across the load i.e.
It is defined as the ratio of dc output power to the applied ac input power i.e.