When A is negative, the diode is
reverse-biased and it does not conduct The reverse
saturation current of a diode is negligible and can
be considered equal to zero for practical purposes (The reverse breakdown voltage of the diode must
be sufficiently higher than the peak ac voltage at
the secondary of the transformer to protect the
diode from reverse breakdown )
Therefore, in the positive half-cycle of ac there
is a current through the load resistor RL and we
get an output voltage, as shown in Fig