Question

Assertion: For a diode in reverse bias, current is independent of applied voltage before breakdown and it increases drastically just after breakdown.
Reason: Before breakdown only majority charge carriers flow.

• A. A & R both correct and R explains A.
• B. A & R both correct and R does not explain A.
• C. A is true but R is false.
• D. A is false but R is true

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Reverse bias behavior in a P-N junction diode involves the flow of minority carriers, creating a very small "reverse saturation current." This current remains constant until the electric field is strong enough to cause ionization (breakdown).
Step 2: Key Formula or Approach:
1. Reverse current \( I \approx I_s \) (Saturation current). 2. Minority carriers: Holes in N-type, Electrons in P-type.
Step 3: Detailed Explanation:
- Assertion: In reverse bias, the depletion layer widens. The only current that flows is due to minority charge carriers, which is independent of the external voltage (saturation). Once the breakdown voltage is reached, the current spikes due to Zener or Avalanche effects. Thus, the Assertion is true.
- Reason: In reverse bias, majority charge carriers are pushed away from the junction, meaning they cannot cross it. The current is actually due to minority charge carriers. Thus, the Reason is false.
Step 4: Final Answer:
Assertion is true but the Reason is false.