JEE Physics 2025 Question with Solution

Given: Five diode circuits (A) to (E) are shown with different polarities and node voltages.

Find: Which circuits have the diode in forward bias.

A diode is forward biased when the anode is at a higher potential than the cathode. In that case, current can flow through the diode.

Check each circuit one by one using the shown polarity and diode orientation:

• (A): anode is at lower potential than cathode, so it is reverse biased.
• (B): anode is at higher potential than cathode, so it is forward biased.
• (C): anode is at higher potential than cathode, so it is forward biased.
• (D): polarity is opposite, so it is reverse biased.
• (E): anode is at higher potential than cathode, so it is forward biased.

Therefore, the circuits representing forward biased diode are (B), (C) and (E) only. Hence, the correct option is C.

Given: Forward bias condition for a diode.

Find: The correct set among the given options.

Condition for forward bias: the diode conducts only when the anode is connected to a higher potential and the cathode is connected to a lower potential. This reduces the barrier and allows current through the diode.

Applying this condition:

1. Option (A): anode at lower potential $\Rightarrow$ reverse bias.
2. Option (B): anode at higher potential $\Rightarrow$ forward bias.
3. Option (C): anode at higher potential $\Rightarrow$ forward bias.
4. Option (D): opposite polarity $\Rightarrow$ reverse bias.
5. Option (E): anode more positive than cathode $\Rightarrow$ forward bias.

So the forward biased diodes are B, C, and E only. Thus, the correct option is C.