Question

A semiconducting device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. The device may be

• A. a $p-$type semiconductor
• B. an intrinsic semiconductor
• C. a $p-n$ junction
• D. an $n$ type semiconductor

Answer 1

Answer: (C)

a $p-n$ junction

Answer 2

When the battery and resistance is connected with $pn$ diode,

In case of forward bias that $p$ is connected to $+$ve terminal of battery, current flows.
If one reverse the polarity i.e., $p$-end is made negative, no current flows in semiconductor diode.