Question

A p-n junction diode is in reverse bias, then
A. More current flows.
B. The barrier potential decreases.
C. The barrier potential increases.
D. Resistance offered is low.

Answer 1

Hint: The width of the depletion layer in the p-n junction diode will get increased in the reverse bias as charge carriers are attracted into battery terminals, holes from p-type into the negative terminal and the electrons from n-type into the positive terminal.

Complete answer:
A p-n junction diode is a device in which there are two-terminal or two-electrode semiconductors in it, and also which permits the electric current in only one direction while preventing the electric current in the opposite or reverse direction. The p-n junction, which is made when the p-type and n-type semiconductors are connected together. The symbol of a diode is given as

The width of the depletion layer in the p-n junction diode will get enhanced in the reverse bias because the charge carriers get attracted into battery terminals, holes from p-type into the negative terminal and the electrons from n-type into the positive terminal.

So, the correct answer is “Option B”.

Note:
When we apply a negative voltage which is actually the reverse bias causes the free charges to be pulled away from the junction which is resulted as the increased width of the depletion layer. This has the effect in increasing or decreasing the total resistance of the junction itself allowing or preventing the flow of current through the diodes in PN-junction. Then the depletion layer gets widened with an enhancement of the application of a reverse voltage and narrows with an increase in the giving of a forward voltage. This is because of the differences in their electrical properties on the two sides of the PN junction which results in physical changes.