Which of the following circuits represents a forward biased diode?
Choose the correct answer from the options given below:

Solution

Physics sir · 3 steps

Find which end is the p-side, then ask one question: is the p-side at the higher potential?

1. Read the symbol. The triangle is the p-side (anode) and the bar is the n-side (cathode). The triangle points in the direction conventional current flows. A diode is forward biased when the anode is at a higher potential than the cathode.
2. Only the difference counts. Signs of the voltages do not matter. -10 V is higher than -15 V, so compare the two numbers on the number line.

   Circuit	Anode (p) at	Cathode (n) at	Bias
   (A)	-10 V (left)	0 V (right)	reverse
   (B)	-10 V (left)	-15 V (right)	forward
   (C)	4 V (left)	2 V (right)	forward
   (D)	-10 V (right)	-5 V (left)	reverse
   (E)	2 V (right)	0 V, ground (left)	forward

3. So. (B), (C) and (E) are forward biased, which is option (d).

The idea to keep. Forward bias means the p-side is at a higher potential than the n-side. Locate the triangle first, then compare the two potentials, even when both are negative.

Answer from the NTA final answer key. Solution by PrepWiser.