Power is consumed in resistance and is equal to IR

Exchange of power takes place between inductor and supply line

Exchange of power takes place between capacitor and supply line

Increases with the increase in supply frequency

Is unaffected by the supply frequency

Decreases with the increase in supply frequency

Becomes zero with the increase in supply frequency

A line which represents the magnitude and phase of an alternating quantity

A line representing the magnitude and direction of an alternating quantity

A colored tag or band for distinction between different phases of a 3-phase supply

An instrument used for measuring phases of an unbalanced 3-phase load

Practice A.C Fundamentals, Circuits And Circuit Theory Multiple Choice Questions Quiz-2

Q.1

Magnitude of current at resonance in R-L-C circuit

Depends upon the magnitude of R
Depends upon the magnitude of L
Depends upon the magnitude of C
Depends upon the magnitude of R, Land C

Q.2

Inductance of a coil Varies

Directly as the cross-sectional area of magnetic core
Directly as square of number of turns
Inversely as the length of the iron path
As A to C

Q.3

The purpose of a parallel circuit resonance is to magnify

Current
Voltage
Power
Frequency

Q.4

The safest value of current the human body can carry for more than 3 second is

4 mA
9 mA
15 mA
25 mA

Q.5

Which of the following waves has the highest value of peak factor ?

Square wave
Sine wave
Half wave rectified sine wave
Triangular wave

Q.6

In a purely inductive circuit

Actual power is zero
Reactive power is zero
Apparent power is zero
None of above is zero

Q.7

Two waves of the same frequency have opposite phase when the phase angle between them is

360°
180°
90°
0°

Q.8

In a highly capacitive circuit the

Apparent power is equal to the actual power
Reactive power is more than the apparent power
Reactive power is more than the actual power
Actual power is more than its reactive power

Q.9

Pure inductive circuit takes power from the A.C. line when

Applied voltage decreases but current increases
Applied voltage increases but current decreases
Both applied voltage and current increase
Both applied voltage and current decrease

Q.10

In a R-L-C circuit

Power is consumed in resistance and is equal to IR
Exchange of power takes place between inductor and supply line
Exchange of power takes place between capacitor and supply line
All above are correct

Q.11

Inductance of coil

Is unaffected by the supply frequency
Decreases with the increase in supply frequency
Increases with the increase in supply frequency
Becomes zero with the increase in supply frequency

Q.12

In R-L-C series resonant circuit magnitude of resonance frequency can be changed by changing the value of

R only
L only
C only
L or C

Q.13

Power factor of the following circuit will be unity

Inductance
Capacitance
Resistance
Both A and B

Q.14

The voltage of domestic supply is 220 V. This figure represents

Mean value
r.m.s. value
Peak value
Average value

Q.15

A parallel AC. circuit in resonance will

Have a high voltage developed across each inductive and capacitive section
Have a high impedance
Act like a resistor of low value
Have current in each section equal to the line current

Q.16

Which of the following circuit component opposes the change in the circuit voltage ?

Inductance
Capacitance
Conductance
Resistance

Q.17

For the same peak value, which of the following wave has the least mean value?

Half wave rectified sine wave
Triangular wave
Sine wave
Square wave

Q.18

In a sine wave the slope is constant

Between 0° and 90°
Between 90° and 180°
Between 180° and 270°
No where

Q.19

For the same peak value which of the following wave will 'have the highest r.m.s. value?

Square wave
Half wave rectified sine wave
Triangular wave
Sine wave

Q.20

The r.m.s. value of pure cosine function is

0.5 of peak value
0.707 of peak value
Same as peak value
Zero

Q.21

If a sinusoidal wave has frequency of 50 Hz with 30 A r.m.s. current which of the following equation represents this wave?

42.42 sin 314 t
60 sin 25 t
30 sin 50 t
84.84 sin 25 t

Q.22

The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is

4 kVAR
6 kVAR
8 kVAR
16 kVAR

Q.23

The double energy transient occur in the

Purely inductive circuit
R-L circuit
R-C circuit
R-L-C circuit

Q.24

A phasor is

A line which represents the magnitude and phase of an alternating quantity
A line representing the magnitude and direction of an alternating quantity
A colored tag or band for distinction between different phases of a 3-phase supply
An instrument used for measuring phases of an unbalanced 3-phase load

Q.25

The phase difference between voltage and current wave through a circuit element is given as 30°. The essential condition is that

Both waves must have same frequency
Both waves must have identical peak values
Both waves must have zero value at the same time
None of the above

Q.26

A heater is rated as 230 V, 10 kW, A.C. The value 230 V refers to

Average voltage
r.m.s. voltage
Peak voltage
None of the above

Q.27

The phosphors for which of the following pair are 180° out of phase for VL, VC and VR?

VC and VR
VL and VR
VC and VL
None of the above

Q.28

The r.m.s. value of half wave rectified sine wave is 200 V. The r.m.s. value of full wave rectified AC. will be

282.8 V
141.4 V
111 V
100 V

Q.29

What will be the phase angle between two alternating waves of equal frequency, when one wave attains maximum value the other is at zero value?

0°
45°
90°
180°

Q.30

The effective resistance of an iron-cored choke working on ordinary supply frequency is more than its true resistance because of

Iron loss in core
Skin effect
Increase in temperature
Capacitive effect between adjacent coil turns