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Question: In a \({{PN}}\) junction: A) High potential at \({{N}}\) side and low potential at \({{P}}\) side ...

In a PN{{PN}} junction:
A) High potential at N{{N}} side and low potential at P{{P}} side
B) High potential at P{{P}} side and low potential at N{{N}} side
C) P{{P}} and N{{N}} both are at the same potential
D) Undetermined

Explanation

Solution

In a PN{{PN}} junction, the P{{P}} side (positive side) has an excess of holes and the N{{N}} side (negative side) has an excess of electrons, therefore the electrons from the N{{N}} side travel to the interface while the holes from the P{{P}} side also travel to the interface leaving a positive charge in N{{N}} side and negative side in P{{P}} side.

Complete solution:
A PN{{PN}} junction is a type of semiconductor. It is an interface at which the P{{P}} type silicon and N{{N}} type silicon have contact with each other. The P{{P}} side contains an excess of electrons or deficiency of electrons and is positively charged while the N{{N}} side has an excess of electrons and is negatively charged. The P{{P}} side can be considered as an anode while the N{{N}} side can be considered as a cathode. The electrons from the N{{N}} side come to the interface and the holes from P{{P}} side also travel to the interface; this interface is known as the depletion region. This leaves behind the N{{N}} side positively charged and the P{{P}} side as negatively charged. Therefore, the current flows fromN{{N}} side to the P{{P}} side. As we know that current flows from the area of higher potential to the area of lower potential therefore N{{N}} side is at higher potential while P{{P}} side is at lower potential.

Note: Although there is no battery connected to the system, then even there will be a flow of current because of the flow of electrons that took place in the diode to fill up the holes which created a net positive charge in the N{{N}} side and a negative charge in the P{{P}} side.