Question

The following circuit is equivalent to

• A. AND gate
• B. NAND gate
• C. NOR gate
• D. OR gate

Hint:

The NAND gate has both inputs joined, so it acts as a NOT gate; two NOT gates cancel, leaving the NOR gate.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept
The figure shows inputs A and B going to a NOR gate. Its output feeds both inputs of a NAND gate, and a NOT gate follows.

Step 2: Output of each stage
NOR output: \(X=\overline{A+B}\).
NAND with both inputs equal to \(X\): \(\overline{X\cdot X}=\overline{X}\), so it acts as a NOT gate.

Step 3: Calculation
After the NAND stage the output is \(\overline{X}=A+B\).
The final NOT gate gives \(Y=\overline{A+B}\).

Step 4: Compare the options
\(Y=\overline{A+B}\) is the NOR operation, option (C).

Final Answer:
The circuit is equivalent to a NOR gate. \[ \boxed{\text{(C) }\text{NOR gate}} \]