The figure, $V_0$ is the barrier potential across a p – n junction, when no battery is connected across the junction.
Answer & explanation
Correct answer: option 2
When p – n junction is forward biased, applied voltage opposes the barrier potential resulting decrease in barrier potential. When p – n junction is reverse biased, applied voltage supports the barrier potential resulting increase in barrier potential. Thus, curve 1 corresponds to reverse bias and curve 3 corresponds to forward bias.