Question

A p-n junction diode acts as a closed switch when it is

• A. Forward biased
• B. Reverse biased
• C. Unbiased
• D. Breakdown biased

Hint:

Remember that forward biasing allows the diode to conduct, making it function like an open switch that has been closed.

Answer 1

The Correct Option is A

Step 1: Understand a diode.
A p-n junction diode lets current flow easily one way but blocks it the other way. A closed switch is one that lets current pass.

Step 2: Look at forward bias.
In forward bias the p-side is connected to the higher potential. This shrinks the barrier inside, so current flows freely. The diode acts like a closed switch.

Step 3: Look at reverse bias.
In reverse bias the barrier grows wider and almost no current flows. The diode acts like an open switch, not a closed one.

Step 4: Look at unbiased.
With no voltage applied the diode does not conduct in any useful way, so it is not a closed switch.

Step 5: Look at breakdown.
The breakdown region is a special high-reverse-voltage state used for special diodes, not a normal closed switch.

Step 6: State the answer.
A diode acts like a closed switch when it is forward biased. \[ \boxed{\text{Forward biased}} \]