Understanding Logic Gate Behavior

Logic gates are the fundamental building blocks of digital electronics. They perform basic logical operations based on binary inputs (represented as 0 for low voltage and 1 for high voltage). This question asks us to identify the logic gate that exhibits a specific behavior: its output is low (0) when any one of its inputs is high (1).

Analyzing Logic Gate Operations

To find the correct logic gate, let's review the standard operations of the gates provided in the options:

• OR Gate: An OR gate outputs a high signal (1) if at least one of its inputs is high (1). The output is low (0) only when all inputs are low (0).
• NOR Gate: A NOR gate is the inverse of an OR gate. Its output is high (1) only when all inputs are low (0). Crucially, if any input is high (1), the output is low (0).
• AND Gate: An AND gate outputs a high signal (1) only if all of its inputs are high (1). If even one input is low (0), the output is low (0).
• NAND Gate: A NAND gate is the inverse of an AND gate. Its output is low (0) only when all inputs are high (1). If any input is low (0), the output is high (1).

Comparing Gate Behaviors with Truth Tables

A truth table provides a clear way to see the output for every possible combination of inputs. Here's a comparison for two-input versions of the gates:

Identifying the Gate with Low Output on High Input

The question specifically asks for the gate where the output is low (0) when one of the inputs is high (1). Let's examine the truth table rows where at least one input is 1:

• When Input A=0 and Input B=1: The NOR gate output is 0.
• When Input A=1 and Input B=0: The NOR gate output is 0.
• When Input A=1 and Input B=1: The NOR gate output is 0.

In all scenarios where at least one input is high (1), the NOR gate consistently produces a low output (0). This matches the condition stated in the question precisely.

Therefore, the NOR gate is the logic gate that has its output low when one of the inputs is high.