# Logic Gates – Exercise – 1

1. A three input NOR gate gives logic high output only when :

(a) One input is high
(b) One input is low
(c) All input are low
(d) All input are high

Explanation
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2. Which one of the following logic gates is a universal logic gate :

(a) NOT
(b) AND
(c) NAND
(d) EX-OR

Explanation
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3. A bulb in a stair case has two switches, one switch being at the ground floor and the other one at the first floor. The bulb can be turned ON and also can be turned OFF by any one of the switches irrespective of the state of the other switch. The logic of switching of the bulb resembles :

(a) AND gate
(b) OR gate
(c) XOR gate
(d) NAND gate

Explanation
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4. For the circuit shown, F is given by :

(a) $\dpi{80} F=XYZ$
(b) $\dpi{80} F=\bar{X}\bar{Y}\bar{Z}$
(c) $\dpi{80} F=X+Y+Z$
(d) $\dpi{80} F=\bar{X}+\bar{Y}+\bar{Z}$
Explanation
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5. In the circuit shown the value of inputs A and B for F = 0 is :

(a) 00
(b) 01
(c) 10
(d) 11