Distinguish clearly between forward biasing and reverse biasing of p-n junction.

Explanation

In forward biasing. The positive terminal of the external battery is connected to p-side and the negative terminal of battery to n-side of p-n junction. Fig. The forward bias voltage opposes the potential barrier. Due to it, the potential barrier is reduced and hence the deplection region becomes thin. The conduction across the p-n junction takes place due to migration of majority carriers from one region to another., i.e., holes from p to n region and electrons from n to p region. the resistance of p-n junction becomes low when forward biased. In reverse biasing, the negative terminal of the external battery is connected to p-side and the positive terminal of battery to n-side of p-n junction. Fig. The reverse biased voltage supports the barrier voltage. Due to it, the size of depletion region increases. The resistance of p-n junction becomes high. The conduction across the p-n junction does not take place due to majority carriers. However if the voltage of the external battery is high, the conduction across the junction takes place due to migration of mionority carriers (i.e. electrons from p-region to n-region and holes from n-region to p-region across the junction) resulting in leakage current or reverse current which is quite weak.