In a PN junction diode, forward bias occurs when which condition holds?

In a PN junction diode, forward bias occurs when which condition holds?

• A. P-type receives a negative charge and N-type receives a positive charge
• B. P-type receives a positive charge and N-type receives a negative charge
• C. Both P and N receive positive charges
• D. Both P and N receive negative charges

Answer: (B)

Forward bias happens when the p-type region is connected to the positive terminal and the n-type region to the negative terminal. This external polarity lowers the built-in potential barrier that naturally blocks carrier flow, narrowing the depletion region. With the barrier reduced, holes from the p-type side and electrons from the n-type side can diffuse across the junction and recombine, allowing current to flow. In this mode the conventional current moves from the p-side toward the n-side. If the polarity were reversed, the barrier would grow and current would stay very small.

Forward bias happens when the p-type region is connected to the positive terminal and the n-type region to the negative terminal. This external polarity lowers the built-in potential barrier that naturally blocks carrier flow, narrowing the depletion region. With the barrier reduced, holes from the p-type side and electrons from the n-type side can diffuse across the junction and recombine, allowing current to flow. In this mode the conventional current moves from the p-side toward the n-side. If the polarity were reversed, the barrier would grow and current would stay very small.