Question

To get output ${}^{\prime }{1}^{\prime }$ at $R$, for the given logic gate circuit the input values must be:

• A. $X=0,Y=1$
• B. $X=1,Y=0$
• C. $X=0,Y=0$
• D. $X=1,Y=1$

Answer 1

The correct option is B $X=1,Y=0$


From the given logic circuit,
Output at $P$
$P=\overline{x}+y$
Output at $Q$
$Q=\overline{\overline{y}.x}=y+\overline{x}$
Output at $R$,
$R=\overline{P+Q}$
To make output $1$
$P+Q$ must be ${}^{\prime }{0}^{\prime }$
$P+Q=(\overline{x}+y)+(y+\overline{x})$
So, $x=1,y=0$ will give the $P+Q=0$
So, the required output
$R=\left(\overline{P+Q}\right)=1$
Hence, option $\left(C\right)$ is correct.