JEE Main · 2025 · 22 Jan 2025 · Shift 1 · Semiconductors

A junction diode conducts (is forward biased) only when its p-side (the anode, marked by the arrowhead of the diode symbol) sits at a higher potential than its n-side (the cathode, the flat bar).

Reading each circuit's anode and cathode potentials from the arrow direction shown:

(A): anode at $-10\text{V}$, cathode at $0\text{V}$ — anode potential is lower than the cathode's, so the diode is reverse biased.

(B): anode at $-10\text{V}$, cathode at $-15\text{V}$ — anode potential exceeds the cathode's, so the diode is forward biased.

(C): anode at $4\text{V}$, cathode at $2\text{V}$ — anode potential exceeds the cathode's, so the diode is forward biased.

(D): anode at $-10\text{V}$, cathode at $-5\text{V}$ — anode potential is lower than the cathode's, so the diode is reverse biased.

(E): anode at $2\text{V}$, cathode at $0\text{V}$ (ground) — anode potential exceeds the cathode's, so the diode is forward biased.

Only diodes (B), (C) and (E) are forward biased.