Which among the characteristics of the crystal diode is used for rectification?
Right Answer is:
Forward
SOLUTION
A PN junction is known as a semiconductor diode or crystal diode.
A PN-junction diode is formed when a p-type semiconductor is fused to an n-type semiconductor creating a potential barrier voltage across the diode junction.
Forward Biasing: If the positive terminal of an external battery is connected to p-type and its negative terminal to n-type of PN junction then such a biasing is called forward biasing. Forward biasing reduces potential barriers and hence, depletion layer width decreases. The current is due to majority carries. Current is quite large when applied, with forward voltage. In forward biasing conditions, the PN junction acts as a Closed switch.
Crystal Diode as a Rectifier
A crystal diode converts a.c. into d.c. and thus acts as a rectifier. Fig. shows the rectifying action of a crystal diode. During the positive half-cycle of a.c. input, the diode is forward biased and conducts current. During the negative half cycle, the diode is reverse biased and conducts no current. The result is that output consists of positive half-cycles of input a.c. voltage while the negative half-cycles are suppressed.
It is interesting to see that the behavior of the diode is like a switch. When the diode is forward biased, it behaves like a closed switch and connects the a.c. supply to the load RL. However, when the diode is reverse biased, it behaves like an open switch and disconnects the a.c. supply from the load RL. This switching action of diode permits only the positive half-cycles of input a.c. voltage to appear across RL.