Identify the correct statements in p-n junction diodes from the following:
(A) In p-n junction, there is diffusion of the majority charge carriers in forward biasing.
(B) The p-n junction diode does act as a closed circuit in reverse biasing.
(C) The diffusion of electrons from n to p and the diffusion of holes from p to n side in p-n in forward bias makes the whole current across the junction.
(D) The conductivity is very low when a voltage more than the cut-in voltage is applied.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A) and (C) only
Forward bias lowers the barrier so majority carriers diffuse across in large numbers; reverse bias raises it, leaving only a tiny minority-carrier current.
(A) In p-n junction, there is diffusion of the majority charge carriers in forward biasing. — Correct. The reduced barrier lets holes from p and electrons from n diffuse across the junction.
(B) The p-n junction diode does act as a closed circuit in reverse biasing. — Incorrect. In reverse bias only a very small current of the order of microamperes flows, so the diode behaves almost as an open circuit.
(C) The diffusion of electrons from n to p and the diffusion of holes from p to n side in p-n in forward bias makes the whole current across the junction. — Correct. The total forward current is the sum of the hole diffusion current and the electron diffusion current.
(D) The conductivity is very low when a voltage more than the cut-in voltage is applied. — Incorrect. Beyond the cut-in voltage the current rises sharply, so the conductivity is high, not low.
NCERT (2026-27):
p-n Junction Diode Under Forward Bias – “… If we increase the applied voltage significantly, the barrier height will be reduced and more number of carriers will have the required energy. Thus the current increases.”
p-n Junction Diode Under Forward Bias – “… The total diode forward current is sum of hole diffusion current and conventional current due to electron diffusion.”
p-n Junction Diode Under Reverse Bias – “… This suppresses the flow of electrons from n → p and holes from p → n. Thus, diffusion current, decreases enormously compared to the diode under forward bias.”