GATE | Gate IT 2005 | Question 10
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 Â Â S2 Â Â Bulb
0 Â Â Â Â 0 Â Â Â On
0 Â Â Â Â 1 Â Â Â Â Off
1 Â Â Â Â 0Â Â Â Â Â Off
1 Â Â Â Â Â 1 Â Â Â Â On
= (S1⊕ S2)’
Therefore answer is C
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Last Updated :
28 Jun, 2021
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