Question

Which semiconductor device is commonly used to regulate or stabilise voltage in a circuit?

Hint:

Think of the diode that is deliberately operated in reverse breakdown.

Answer 1

Step 1. A voltage regulator device must keep the output voltage almost constant even if the input voltage or the load current changes.
Step 2. The device commonly used for this job is the Zener diode, a special type of p-n junction diode.
Step 3. A Zener diode is designed to be operated in reverse bias, deliberately pushed into a controlled reverse breakdown region called the Zener breakdown region.
Step 4. In this breakdown region, the voltage across the diode stays almost fixed at a value called the Zener voltage, even though the current through it can change over a wide range. Placing this diode across the load holds the load voltage steady.
Answer. The device used to regulate voltage is the Zener diode.