Question

The special purpose diode operated / working under forward bias is / are

• A. zender diode and LED
• B. photo diode and LED
• C. zener diode and solar cell
• D. LED
• E. photo diode

Answer 1

The Correct Option is D

A diode works under forward bias when a positive voltage is applied to the anode, allowing current to flow through the diode.

• Zener diode operates in reverse bias, where it allows current to flow in reverse direction when a certain breakdown voltage is reached. Therefore, it does not work under forward bias.
• LED (Light Emitting Diode) works under forward bias, and it emits light when current passes through it.
• Photo diode operates in reverse bias, where it generates current in response to light.
• Solar cell works under reverse bias as well.

Thus, the correct answer is LED, which operates under forward bias.

The correct option is (D) : LED

Answer 2

The Light Emitting Diode (LED) is a special-purpose diode that operates under forward bias. When forward biased, it emits light due to recombination of electrons and holes in the semiconductor material. 
 
Other special-purpose diodes like:

• Zener diode: typically used in reverse bias for voltage regulation.
• Photo diode: used in reverse bias to detect light.
• Solar cell: operates like a photodiode in reverse bias generating current from light.

✅ Correct Answer: LED