Engineering Questions with Answers - Multiple Choice Questions

# Basic Electrical Engineering MCQ’s – Inductive and Non-Inductive Circuits

1 - Question

In case of Inductive circuit, Frequency is ______________ to the inductance.
a) Directly proportional
b) Inversely proportional
c) Unrelated
d) Much greater than

Explanation: The formula for frequency in an inductive circuit is:
XL=2*π*f*L.
Therefore: f is inversely proportional to L.

2 - Question

In case of Inductive circuit, Frequency is ______________ to the current.
a) Directly proportional
b) Inversely proportional
c) Unrelated
d) Much greater than

Explanation: The formula for frequency in an inductive circuit is:
XL=2*π*f*L => i=V/(2*π*f*L)
Therefore: f is inversely proportional to i.

3 - Question

In an inductive circuit, when the XL value increases, the circuit power factor?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero

Explanation: tan ϕ = XL/R and Power factor=cos ϕ
As XL increases, tan ϕ increases, ϕ increases, cos ϕ decreases and hence power factor decreases.

4 - Question

If the current and voltage are 90 degrees out of phase, the power factor will be?
a) 0
b) Infinity
c) 1
d) Insufficient information provided

Explanation: The power factor is the cosine of the angle between the voltage and the current. If the angle between the voltage and the current is 90, then cos90=0. Hence, the power factor is zero.

5 - Question

In a pure inductive circuit, the power factor is __________
a) Maximum
b) Minimum
c) 0
d) Infinity

Explanation: In a pure inductive circuit, the current is lagging by 90 degrees from the voltage. The power factor is the cosine of the angle between the voltage and the current. If the angle between the voltage and current is 90, then cos90=0. Hence, the power factor is zero.

6 - Question

If the power factor is 1/10 and the value of impedance is 20 ohm, calculate the resistance in the circuit.
a) 1 ohm
b) 2 ohm
c) 3 ohm
d) 4 ohm

Explanation: We know that:
cos(ϕ)=R/Z
R=Z cos(ϕ) = 20/10 = 2 ohm.

7 - Question

If the resistance in a circuit is 2 ohm and the impedance is 20 ohm, calculate the power factor.
a) 1/10
b) 1/20
c) 1/30
d) 1/40

Explanation: We know that:
cos(ϕ)=R/Z = 2/20 = 1/10 ohm.

8 - Question

If tan ϕ = 10 and the resistance is 2 ohm, calculate the inductive reactance.
a) 10 ohm
b) 20 ohm
c) 30 ohm
d) 40 ohm

Explanation: We know that:
tan(ϕ)=XL/R
From the given question, we find that the inductive reactance is 20 ohm.

9 - Question

What is the unit for inductive reactance?
a) Henry
b) Ohm
d) Volts

Explanation: Inductive reactance is nothing but the impedance. Impedance is the AC equivalent of resistance, hence the unit for inductive reactance is ohm.

10 - Question

An induced emf is said to be ________
a) Inductive
b) Capacitive
c) Resistive
d) Cannot be determined