Question

The pn junction diode acts as a rectifier because:

• A. it conducts in both directions
• B. it blocks current in reverse bias
• C. it allows ac to pass
• D. it amplifies the signal
• E. it offers a phase difference between voltage and current

Hint:

A diode acts like a one-way valve for current: forward → ON, reverse → OFF.

Answer 1

The Correct Option is B

Step 1: Understand rectification.
Rectification means converting alternating current (AC) into direct current (DC).

Step 2: Behavior of pn junction.
A pn junction diode allows current to pass in forward bias and blocks it in reverse bias.

Step 3: Role in AC circuit.
During AC cycle: - Positive half → diode conducts
- Negative half → diode blocks

Step 4: Resulting output.
Only one half-cycle passes → produces pulsating DC.

Step 5: Eliminate incorrect options.
- Does not conduct both ways
- Does not amplify
- Does not create phase difference

Step 6: Key reason.
Blocking current in reverse bias is the fundamental reason for rectification.

Step 7: Final conclusion.
\[ \boxed{\text{It blocks current in reverse bias}} \] Therefore, the correct option is \[ \boxed{(2)} \]