Question

What is the output of a NAND gate when both inputs are HIGH?

• A. \( \text{HIGH} \)
• B. \( \text{LOW} \)
• C. \( \text{Alternates between HIGH and LOW} \)
• D. \( \text{Indeterminate} \)

Hint:

NAND gates are universal gates, meaning they can be used to construct any other type of logic gate. The key feature of the NAND gate is that its output is always HIGH unless all of its inputs are HIGH, in which case the output is LOW.

Answer 1

The Correct Option is B

A NAND gate (NOT-AND gate) is a fundamental digital logic gate that produces an output which is the negation of the AND gate. It is one of the most widely used gates in digital circuits, particularly because it is a universal gate, meaning any other logic gate can be constructed using only NAND gates. The truth table for a NAND gate is as follows:

Step 1: Analyze the given inputs.

Input A	Input B	Output Y (NAND)
0	0	1
0	1	1
1	0	1
1	1	0

When both inputs \( A \) and \( B \) are HIGH (\( 1 \)):

\[ Y = \text{NOT} (A \cdot B). \]

In this case, \( A \cdot B = 1 \cdot 1 = 1 \), since the AND operation yields 1 when both inputs are 1.

Step 2: Apply the NOT operation.

Next, we negate the result of the AND operation:

\[ Y = \text{NOT}(1) = 0. \]

Conclusion:

Thus, the output of the NAND gate is LOW (\( 0 \)) when both inputs are HIGH. Therefore, the correct answer is \( \mathbf{(2)} \).