AND gate behavior Under what input condition is the output of an AND gate LOW?

Introduction / Context:
Logic gates implement Boolean operations. The AND gate outputs TRUE (logic 1) only when all its inputs are TRUE. Understanding its truth table is essential for designing combinational logic and control circuits.

Given Data / Assumptions:

• Ideal AND gate with two or more inputs.
• Positive logic convention (HIGH = 1, LOW = 0).

Concept / Approach:
Boolean AND corresponds to multiplication in binary algebra: 1 * 1 = 1; any term being 0 forces the product to 0. Thus, a single LOW input guarantees a LOW output, regardless of other inputs.

Step-by-Step Solution:

Verification / Alternative check:
Construct the truth table for a two-input AND: (0,0)→0; (0,1)→0; (1,0)→0; (1,1)→1. This generalizes to more inputs: a single 0 yields 0 output.

Why Other Options Are Wrong:

• All the time: An AND gate can output HIGH when all inputs are HIGH.
• When any input is HIGH: That describes OR-like behavior, not AND.
• When all inputs are HIGH: That is when the output is HIGH, not LOW.

Common Pitfalls:
Confusing AND with OR; misreading active-low logic symbols; forgetting positive vs. negative logic conventions.

Final Answer:
when any input is LOW