Question

In a reversed-biased p-n junction diode, the applied voltage mostly drops across :

• A. p-region only
• B. n-region only
• C. depletion region
• D. the diode

Hint:

In reverse bias, the depletion layer widens and behaves like a high-resistance region. Therefore, almost the entire reverse voltage appears across the depletion region.

Answer 1

The Correct Option is C

Concept: A p-n junction consists of: \[ \text{p-region} \] and \[ \text{n-region}. \] At the junction, diffusion of charge carriers creates a depletion region containing immobile ions. This depletion region behaves as an insulating layer and possesses very high resistance compared to the p-region and n-region.

Step 1: Understand reverse biasing. In reverse bias, \[ p\text{-side} \] is connected to the negative terminal and \[ n\text{-side} \] is connected to the positive terminal. The external voltage increases the width of the depletion layer.

Step 2: Analyze the resistance of different regions. The p-region and n-region contain majority charge carriers and therefore possess relatively low resistance. The depletion region contains almost no free charge carriers and therefore has very high resistance.

Step 3: Apply the voltage division principle. In any circuit, the larger voltage drop occurs across the region having the larger resistance. Since the depletion region offers maximum resistance, \[ \text{most of the applied reverse voltage} \] appears across the depletion region.

Step 4: Write the final conclusion. Hence, in a reverse-biased p-n junction diode, the applied voltage mostly drops across the \[ \boxed{\text{depletion region}}. \] Therefore, \[ \boxed{\text{(C)}} \] is the correct answer.