Four diode connections are given below. Identify the diagram in which the diode is forward biased.
Choose the correct answer from the options given below.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (B) and (D) only
A diode is forward biased when its p-side (anode, the triangle side of the symbol) is at a higher potential than its n-side (cathode, the bar side). The resistor in series does not change which end is higher.
(A) Anode at 0 V (earth), cathode at +5 V — anode lower, so reverse biased.
(B) Anode at +10 V, cathode at +5 V — anode higher, so forward biased.
(C) Anode at −10 V, cathode at 0 V (earth) — anode lower, so reverse biased.
(D) Anode at −5 V, cathode at −12 V — anode higher (−5 V is above −12 V), so forward biased.
NCERT (2026-27):
p-n Junction Diode Under Forward Bias – “When an external voltage V is applied across a semiconductor diode such that p-side is connected to the positive terminal of the battery and n-side to the negative terminal [Fig. 14.13(a)], it is said to be forward biased.”