Question

The output of a $NOR$ gate is HIGH when

• A. all inputs are HIGH
• B. any input is HIGH
• C. any input is LOW
• D. all inputs are LOW

Answer 1

Answer: (D)

The Boolean expression of $NOR$ gate is
$Y=\overline{A+B}$
where, $A$ and $B$ are inputs and $Y$ is the output.
Truth table of $NOR$ gate is

$A$	$B$	$Y=\overline{A+B}$
$0$	$0$	$1$
$0$	$1$	$0$
$1$	$0$	$0$
$1$	$1$	$0$

Hence, when all inputs $(A$ and $B)$ are low $(0)$, then output of $NOR$ gate is high $(1)$.