A two-way switch has three terminals a, b and c. In ON position (logic value 1), a is connected to b, and in OFF position, a is connected to c. Two of these two-way switches S1 and S2 are connected to a bulb as shown below.
Which of the following expressions, if true, will always result in the lighting of the bulb ?
(A) S1.S2′
(B) S1+S2
(C) (S1⊕S2)’
(D) S1⊕S2
Answer: (C)
Explanation: If we draw truth table of the above circuit,it’ll be
S1 S2 Bulb
0 0 On
0 1 Off
1 0 Off
1 1 On
= (S1⊕ S2)’
Therefore answer is C
Quiz of this Question