Engineering Questions with Answers - Multiple Choice Questions

# MCQs on Logic Circuits

1 - Question

. If there are ‘M’ switches in series numbered from 1, 2, …, M. For circuit to be complete and bulb to glow which of the following is necessary?
a) 1∧ 2∧ 3 ∧ … ∧M should be on
b) 1∧ 2∧ 3 ∧ … ∧M should be off
c) 1 v 2 v 3 v … v M should be on
d) None of the mentioned

Explanation: All should be on in-order to complete the circuit.

2 - Question

If there are ‘M’ switches in parallel numbered from 1, 2, …, M. For circuit to be complete and bulb to glow which of the following is necessary
a) 1∧ 2∧ 3 ∧ … ∧M should be on
b) 1∧ 2∧ 3 ∧ … ∧M should be off
c) 1 v 2 v 3 v … v M should be on
d) None of the mentioned

Explanation: Anyone should be on in-order to complete the circuit.

3 - Question

In the circuit shown the lamp will be glowing if _________ a) P: True, Q: False
b) P: True, Q: True
c) P: False, Q: False
d) None of the mentioned

Explanation: The circuit will be complete if P is true and Q is false

4 - Question

In this circuit shown the lamp will be glowing if _________ a) P: True, Q: True, R: False
b) P: True, Q: True, R: True
c) P: False, Q: False, R: True
d) None of the mentioned

Explanation: The circuit will be complete if R is true and Q is false or P is false.

5 - Question

Which statement should be true in order for lamp to glow? a) (R ∧ (~(P ∧ Q))
b) P∧R∧Q
c) P ∧ (Q ∧ ~R)
d) None of the mentioned

Explanation: The circuit will be complete if R is true and Q is false or P is false.

6 - Question

If it is given that switch R is closed and Q is closed then lamp will glow if _________ a) P: Open, S: Closed
b) P: Open, S: Open
c) P: Closed, S: Closed
d) None of the mentioned

Explanation: The circuit will be complete if (~P) is true and S is true

7 - Question

The circuit depend on which switch/switches state to be complete? a) P
b) Q
c) Both P and Q
d) None of the mentioned

Explanation: The circuit will be complete if (P) is true, Q v ~Q will always be true.

8 - Question

The ten switches A,B,C,D,E,F,G,H,N,M are placed in the given circuit (all are open at given time). If you close one switch you need to pay 1 unit cost. What is the cost you need to pay to glow this Lamp? a) 1 unit
b) 2 units
c) 3 units
d) 4 units

Explanation: This can be achieved by turning one of switches N or M on.

9 - Question

If in a for it to be complete it is necessary for switch A to be closed and either of switch B or C to be closed, then which can be true?
a) Switch A should in parallel with B and C is series to them
b) Switch A should be in series with a parallel circuit of B and C
c) All of the mentioned
d) None of the mentioned

Explanation: Switch A is in series and since there is ‘or’ between B and C therefore they must be in parallel.

10 - Question

The given circuit can work if the switches P and Q be ___________ a) P: True, Q: False
b) P: True, Q: True
c) P: False, Q: False
d) All of the mentioned