Which of the following circuits provides full-wave rectification of an $A.C.$ input?

If a square signal of $10 \ V$ (varying from $+5 \ V$ to $-5 \ V$) is applied to a $P-N$ junction diode as shown,the output signal across $R_L$ will be:

An ideal diode is connected in a circuit with resistance $R = 50\ \Omega$ and battery $V = 10\ V$ as shown in the figure. What are the maximum and minimum values of the output voltage when no load is applied?

The maximum efficiency of a full-wave rectifier is .........$\%$

In a half-wave rectifier using a $PN$ junction diode, the input voltage has an amplitude of $25 \ V$ and a frequency of $50 \ Hz$. No filter is used, and the load resistance is $1000 \ \Omega$. The forward resistance of the diode is $10 \ \Omega$. The efficiency of the rectifier is approximately ...... $\%$.

If the maximum efficiency of a full wave rectifier is $x \%$ and that of a half wave rectifier is $y \%$,then the relation between $x$ and $y$ is