Question

For an ideal diode, in forward and reverse biased condition the resistance is respectively

• A. infinite, zero.
• B. infinite, infinite.
• C. zero, zero.
• D. zero, infinite.

Hint:

Think of an ideal diode as a one-way switch. Closed (Forward) = No Resistance; Open (Reverse) = Infinite Resistance.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
A p-n junction diode acts as a one-way valve for electric current. It allows current to flow easily in one direction (forward bias) and severely restricts it in the opposite direction (reverse bias).
An "ideal" diode is a theoretical model that perfectly exhibits this behavior without any non-ideal characteristics like voltage drops or leakage currents.
Step 2: Key Formula or Approach:
The defining characteristics of an ideal diode are:
1. In the forward-biased condition, it acts as a perfect short circuit, meaning it offers zero opposition to current flow.
2. In the reverse-biased condition, it acts as a perfect open circuit, meaning it completely blocks current flow.
Step 3: Detailed Explanation:
Based on the ideal model:
- Forward Bias Resistance: Since it acts as a short circuit, the resistance is exactly zero ($0\ \Omega$).
- Reverse Bias Resistance: Since it acts as an open circuit (no current flows regardless of the applied voltage), the resistance is considered to be infinite ($\infty\ \Omega$).
Therefore, the resistance values are zero and infinite, respectively.
Step 4: Final Answer:
The resistance is zero, infinite respectively.