Question

The circuit given represents which of the logic operations ?

• A. OR
• B. NOR
• C. NOT
• D. AND

Answer 1

The Correct Option is B

Correct Answer: B (NOR)

Explanation: The circuit represents a NOR gate because:

• Structure: A NOR gate is equivalent to an OR gate followed by a NOT gate (inverter).
• Behavior: The output is HIGH (1) only when both inputs are LOW (0), matching the NOR truth table.

Why other options are incorrect:

• A (OR): OR gates lack the final inversion step.
• B (AND): AND gates require both inputs to be HIGH for a HIGH output.
• C (NOT): NOT gates have only one input, not two.

Key Insight: The inversion (bubble) at the output signifies the NOT operation combined with OR, defining NOR logic.

Answer 2

1. Identify the gates:

- The first gate is an OR gate. OR gate is shown as a curved shape followed by a D shape.

- The second gate is a NOT gate represented by a small circle (bubble) at the final end of the second OR gate symbol. So, the second gate shown is a NOT-OR gate (NOR gate).

2. OR Gate Function:

An OR gate outputs a '1' (HIGH) if either or both of its inputs are '1'. It outputs a '0' (LOW) only if both inputs are '0'.

3. NOT Gate Function:

A NOT gate (also called an inverter) takes a single input and outputs the opposite value. If the input is '1', the output is '0', and vice versa.

4. NOR Gate Combined Function:

A NOR gate is the combination of an OR gate and a NOT gate. It essentially performs the OR operation and then inverts the result. In other words, a NOR gate outputs a '1' only if *both* of its inputs are '0'. If either or both inputs are '1', the output is '0'.

Therefore, the complete circuit represents a NOR gate operation.

Final Answer: (D) NOR