Question

Find the symbolic form of the following switching circuit, construct its switching table and interpret it.

Answer 1

Symbolic form $=(S_1+S_2^{\prime })+(S_1^{\prime }.S_2)$
Switching table

$S_1$	$S_2$	$S_1^{\prime }$	$S_2^{\prime }$	$S_1+S_2^{\prime }$	$S_1^{\prime }{S}_2$	$S_1+S_2^{\prime }+S_1^{\prime }{S}_2$
$T$	$T$	$F$	$F$	$T$	$F$	$T$
$T$	$F$	$F$	$T$	$T$	$F$	$T$
$F$	$T$	$T$	$F$	$F$	$T$	$T$
$F$	$F$	$T$	$T$	$T$	$F$	$T$

All the entries in the last column of the above truth table are $T$
$\therefore$ $S_1+S_2^{\prime }+S_1^{\prime }{S}_2$ is a tautology.