Which of the following statements are correct?
(A) The current under reverse bias is essentially voltage dependent on a critical reverse bias voltage.
(B) The diode gets destroyed due to overheating if the forward or reverse current exceeds the rated value.
(C) In forward bias measurement, we use a milliammeter since the expected current is large, while a microammeter is used in reverse bias to measure the current.
(D) The drift current is of the order of a few μA
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (B), (C) and (D) only
Under reverse bias only the minority carriers cross the junction, giving a tiny drift current that hardly changes with voltage until the breakdown voltage is reached.
(A) The current under reverse bias is essentially voltage dependent on a critical reverse bias voltage. — Incorrect. The reverse current is almost independent of the voltage up to the critical (breakdown) voltage, because it is limited by the number of minority carriers, not by the applied voltage.
(B) The diode gets destroyed due to overheating if the forward or reverse current exceeds the rated value. — Correct. A large current produces excessive heat at the junction.
(C) In forward bias measurement, we use a milliammeter since the expected current is large, while a microammeter is used in reverse bias to measure the current. — Correct. The forward current is of the order of mA, while the reverse current is only of the order of μA.
(D) The drift current is of the order of a few μA. — Correct. The drift current is carried by the few minority carriers, so it is very small.
NCERT (2026-27):
p-n Junction Diode Under Reverse Bias – “… The drift current is of the order of a few μA.”
p-n Junction Diode Under Reverse Bias – “… The current under reverse bias is essentially voltage independent upto a critical reverse bias voltage, known as breakdown voltage (Vbr). … Once it exceeds the rated value, the diode gets destroyed due to overheating. This can happen even for the diode under forward bias, if the forward current exceeds the rated value. … Note that in forward bias measurement, we use a milliammeter since the expected current is large (as explained in the earlier section) while a micrometer is used in reverse bias to measure the current.”