In the half wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be

25 Hz 50 Hz 70.7 Hz 100 Hz

50 Hz

In half wave rectifier, we get the output only in one half cycle of input a.c. therefore, the frequency of the ripple of the output is same as that of input a.c. i.e. 50 Hz