$A$ $p-n$ junction diode as a rectifier converts

The maximum efficiency of a full wave rectifier is .........

$A$ full-wave rectifier with diodes $D_1$ and $D_2$ is used to rectify $50 \,Hz$ alternating voltage. The diode $D_1$ conducts .......... times in one second.

The input a.c. voltage of frequency $60 \,Hz$ is applied to a half-wave rectifier and also to a full-wave rectifier. The output frequency in the case of the half-wave rectifier and that in the case of the full-wave rectifier is respectively:

The figure below shows a circuit and its input voltage $V_i$ as a function of time $t$. Assuming the diodes to be ideal,which of the following graphs depicts the output voltage $V_o$ as a function of time $t$?

$A$ $PN$ junction diode is used as: