Question

To get output 1 for the following logic circuit, the correct choice of the inputs is: 

• (1) A = 1, B = 1, C = 0
• (2) A = 0, B = 1, C = 0
• (3) A = 1, B = 0, C = 1
• (4) A = 0, B = 0, C = 1

Hint:

In NAND gates, the output is 1 when either of the inputs is 0. A NAND gate only outputs 0 when both inputs are 1.

Answer 1

The Correct Option is C

The logic circuit shown involves a combination of NAND gates. Let's break down the behavior of the circuit based on the inputs:

1. The first gate is a NAND gate. A NAND gate outputs 1 unless both its inputs are 1.

For inputs A = 1, B = 0 at this gate, the output will be 1 (since \(1 \cdot 0 = 0\), and the NAND of 0 is 1).

2. The second gate is another NAND gate. The input to this gate comes from the output of the first gate and the input C.

 Now, the input to the second gate will be \(1 \text{ (from the first NAND gate)}\) and \(C = 1\).

 Since the NAND of \(1 \cdot 1 = 1\), the output of the second gate will be 0.

Thus, the correct inputs that produce the output 1 are:

A = 1, B = 0, C = 1

Hence, the correct choice is Option (3).