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 inverts the output of an AND gate. It is widely used in digital circuits due to its universality, meaning all other logic gates can be built using only NAND gates. The truth table for a NAND gate is presented below:

Step 1: Examine the provided 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 scenario, \( A \cdot B = 1 \cdot 1 = 1 \), as the AND operation results in 1 only when both inputs are 1.

Step 2: Apply the NOT operation.

Subsequently, the result of the AND operation is negated:

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

Conclusion:

Consequently, the NAND gate's output is LOW (\( 0 \)) when both inputs are HIGH. Therefore, the correct selection is \( \mathbf{(2)} \).