The capacitor smoothens out the fluctuation from the rectifier, but still some ripple is obtained as seen! Half wave uses only one diode, so voltage drop is less. It ELIMINATES the negative part of the AC waveform and so the waveform becomes n_n_n_n like only the top part stays! In a full wave rectifier, 2 diodes are active, so the voltage drop is more. It INVERTS the negative part of the AC waveform, forming a waveform like this mmmmmmm like the McDonald's arches. So it utilizes the whole original waveform and it has half the magnitude of ripple that a HWR has! The n_n_n_n_ or mmm as the case may be, is smoothed out using a capacitor forming the waveforms as seen here!
