Question

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : A Zener diode is used for voltage regulation. Reason (R) : It maintains a nearly constant voltage in reverse breakdown region. In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• C. (A) is correct but (R) is not correct
• D. (A) is not correct but (R) is correct

Hint:

Zener diode works in: \[ \text{Reverse breakdown region} \] and maintains: \[ V \approx \text{constant} \] Therefore it is widely used as a voltage regulator.

Answer 1

The Correct Option is A

Concept: A Zener diode is specially designed to operate in reverse breakdown region. Its most important property is: \[ \text{Nearly constant voltage during reverse breakdown} \] This makes it highly suitable for voltage regulation applications.

Step 1: Understanding Assertion (A). Assertion says: \[ \text{A Zener diode is used for voltage regulation} \] This statement is correct. In electronic circuits:
• supply voltage may fluctuate,
• load current may change,
• output voltage must remain stable. A Zener diode helps maintain constant output voltage.

Step 2: Understanding Reason (R). Reason says: \[ \text{It maintains nearly constant voltage in reverse breakdown region} \] This statement is also correct. Once reverse voltage reaches: \[ V_Z \] the diode conducts heavily but voltage across it remains approximately constant.

Step 3: Understanding why voltage regulation occurs. Suppose: \[ V_Z = 5.1V \] Even if current changes significantly: \[ V_Z \approx 5.1V \] Hence:
• output voltage remains stable,
• voltage variations are minimized. This is exactly the principle of voltage regulation.

Step 4: Checking explanation relationship. Reason correctly explains Assertion because:
• constant breakdown voltage property,
• directly leads to voltage regulation action. Hence:
• Assertion is correct,
• Reason is correct,
• Reason correctly explains Assertion.

Step 5: Selecting the correct answer. Thus the correct option is: \[ \boxed{(1)} \]