AND gate truth – if all inputs are HIGH, is the output LOW?

Introduction / Context:
The AND function is one of the core Boolean primitives. Knowing the output when all inputs are asserted is essential for designing enable signals, decoders, and control logic.

Given Data / Assumptions:

• Standard AND gate with two or more inputs.
• Active-HIGH logic levels.
• No inversion bubbles at the output (i.e., not a NAND).

Concept / Approach:
For an AND gate, the output is 1 only if every input is 1. Therefore, if all inputs are HIGH, the output must be HIGH. The statement claims the output would be LOW in that case, which is the opposite and would correspond to a NAND gate, not an AND gate.

Step-by-Step Solution:

Verification / Alternative check:
Consult truth tables: AND(1,1) = 1; AND(1,1,1) = 1. Only NAND gives 0 for all-HIGH inputs. Schematic symbols with an inversion bubble at the output indicate NAND, not AND.

Why Other Options Are Wrong:
“Correct” conflicts with the AND definition. “Only for three or more inputs” is irrelevant; any number of inputs follows the same rule. “Only with active-LOW outputs” confuses electrical polarity with logic function. “Cannot be determined” is incorrect; the AND definition is precise.

Common Pitfalls:
Mixing up AND and NAND due to similar symbols. Always check for the small inversion bubble to identify NAND, which inverts the AND result.

Final Answer:
Incorrect