EEE - Inductors Quiz (or) MCQ | Questions and Answers

1 .

A 5 mH, a 4.3 mH, and a 0.6 mH inductor are connected in parallel. The total inductance is ___.

A)

9.9 mH

B)

Greater than 5 mH

C)

Less than 0.6 mH

D)

9.9 mH or greater than 5 mH

Correct Answer : Less than 0.6 mH

2 .

A 2 mH, a 3.3 mH, and a 0.2 mH inductor are connected in series. The total inductance is

A)

5.5 mH

B)

55 mH

C)

less than 0.2 mH

D)

less than 5.5 mH

Correct Answer : 5.5 mH

3 .

An inductance of 0.08 ÂµH is larger than

A)

0.000008 H

B)

0.0000008 H

C)

0.00008 mH

D)

0.000000008 H

Correct Answer : 0.000000008 H

4 .

An inductance of 0.43 mH is smaller than

A)

0.00043 H

B)

0.05 H

C)

43 ÂµH

D)

430 ÂµH

Correct Answer : 0.05 H

5 .

The winding resistance of a coil can be increased by

A)

Using a thinner wire

B)

Changing the core material

C)

Increasing the number of turns

D)

Increasing the number of turns or using thinner wire

Correct Answer : Increasing the number of turns or using thinner wire

6 .

An 18 V power supply is connected across a coil with a winding resistance of 180 Ω. Current flow in the coil is

A)

1 A

B)

1 mA

C)

10 mA

D)

100 mA

Correct Answer : 100 mA

7 .

Faraday's law states that relative motion between a magnetic field and a coil induces a voltage across the coil.

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

8 .

Inductance is indirectly proportional to the square of the number of turns, the permeability, and the cross-sectional area of the core.

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

9 .

A sine wave voltage is applied across an inductor. When the frequency of the voltage is decreased, the current

A)

Is decreased

B)

Is increased

C)

Does not change

D)

Momentarily goes to zero

Correct Answer : Is increased

10 .

The current through a 120 mH coil is changing at a rate of 150 mA/s. The voltage induced across the coil is

A)

1.25 mV

B)

1.8 mV

C)

18 mV

D)

180 mV

Correct Answer : 18 mV

11 .

An ohmmeter is connected across an inductor and the pointer indicates zero ohms. The inductor is

A)

Open

B)

Shorted

C)

Good

D)

Partly shorted

Correct Answer : Shorted

12 .

When the current through an inductor decreases, the amount of energy stored in the electromagnetic field

A)

Increases

B)

Decreases

C)

Doubles

D)

Remains the same

Correct Answer : Decreases

13 .

When the current through an inductor is cut in half, the amount of energy stored in the electromagnetic field

A)

Is quartered

B)

Doubles

C)

Quadruples

D)

Does not change

Correct Answer : Is quartered

14 .

The following coils are in parallel: 75 ÂµH, 40 ÂµH, 25 ÂµH, and 15 ÂµH. The total inductance is approximately

A)

155 ÂµH

B)

14 ÂµH

C)

6.9 ÂµH

D)

2.2 ÂµH

Correct Answer : 6.9 ÂµH

15 .

An induced voltage is produced as a result of a dc voltage.

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : False

16 .

Inductance is the property of an inductor that produces an opposition to any change in current.

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

17 .

An inductor and a resistor are in series with a sine wave voltage source. The frequency is set so that the inductive reactance is equal to the resistance. If the frequency is increased, then

A)

VR = VL

B)

VL < VR

C)

VL = VR

D)

VL > VR

Correct Answer : VL > VR

18 .

The term 'self-inductance' is used when a conductor has a voltage induced in it by :

A)

a nearby magnetic field

B)

nearby electromotive force

C)

its own electromotive force

D)

its own magnetic field

Correct Answer : its own magnetic field

19 .

What is magnetic flux?

A)

The number of lines of force in teslas

B)

The number of lines of force in maxwells

C)

The number of lines of force in webers

D)

The number of lines of force in flux density

Correct Answer : The number of lines of force in webers

20 .

An inductor, a 1 kΩ resistor, and a switch are connected in series across a 6 V battery. At the instant the switch is closed, the inductor voltage is

A)

0 V

B)

4 V

C)

6 V

D)

12 V

Correct Answer : 6 V

21 .

Five inductors are connected in series. The lowest value is 8 µH. If the value of each inductor is twice that of the preceding one, and if the inductors are connected in order of ascending values, the total inductance is

A)

8 H

B)

32 µH

C)

64 µH

D)

248 µH

Correct Answer : 248 µH

22 .

Three 15 mH inductors are in series. The total inductance is

A)

5 mH

B)

15 mH

C)

30 mH

D)

45 mH

Correct Answer : 45 mH

23 .

Which type of inductor is used for tuning circuits like radio?

A)

Toroidal core

B)

Variable core

C)

Air core

D)

Ferrite core

Correct Answer : Variable core

24 .

The tapped inductors are ______________ type of inductors

A)

Fixed

B)

Variable

C)

Both (A) and (B)

D)

None of the above

Correct Answer : Variable

25 .

The inductance of an iron-core coil decreases if

A)

the iron core is removed

B)

the length of the coil decreases

C)

the number of turns is decreased

D)

None of the above

Correct Answer : the number of turns is decreased

26 .

Two 10 H inductors are in parallel and the parallel combination is in series with a third 10 H inductor. What is the approximate total reactance when a voltage with a frequency of 7 kHz is applied across the circuit terminals?

A)

1.3 MΩ

B)

66 kΩ

C)

219 kΩ

D)

660 kΩ

Correct Answer : 660 kΩ

27 .

Energy is stored by an inductor in an electrostatic field.

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : False

28 .

The term 'choke' is more commonly used in connection with an inductor used to block off high frequencies.

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

29 .

A switch, a 220 Ω resistor, and a 60 mH inductor are in series across a 20 V battery. What is the current through the inductor two time constants after the switch is closed?

A)

57 mA

B)

78 mA

C)

91 mA

D)

400 mA

Correct Answer : 78 mA

30 .

Inductors add in parallel.

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : False

31 .

A 320 µH coil is in series with a 3.3 kΩ resistor. How long does it take for current to build up to its full value?

A)

0.48 s

B)

0.48 ms

C)

0.48 µs

D)

48 s

Correct Answer : 0.48 µs

32 .

Two inductors, L1 and L2, are in parallel. L1 has a value of 25 µH and L2 a value of 50 µH. The parallel combination is in series with L3, a 20 µH coil. The entire combination is across an ac source of 60 Vrms at 300 kHz. The total rms current is

A)

87 A

B)

87 mA

C)

337 mA

D)

870 mA

Correct Answer : 870 mA

33 .

A 240 ÂµH inductor is equivalent to a

A)

0.000240 mH inductor

B)

240 mH inductor

C)

240 H inductor

D)

0.240 mH inductor

Correct Answer : 0.240 mH inductor

34 .

Opposition to current flow without the dissipation of energy is called __________.

A)

impedance

B)

resistance

C)

counter emf

D)

inductive reactance

Correct Answer : inductive reactance

35 .

The direction of induced e.m.f. can be found by which of the following law?

A)

Lenz's law

B)

Laplace's law

C)

Kirchhoff's voltage law

D)

Fleming's right hand rule

Correct Answer : Lenz's law

36 .

Mutual inductance between two magnetically coupled coils depends on:

A)

Number of turns of the coils

B)

Permeability of the core material

C)

Cross sectional area of their common core

D)

All of the above

Correct Answer : All of the above

37 .

An open coil has __________.

A)

Zero resistance and inductance

B)

Zero resistance and high inductance

C)

Infinite resistance and zero inductance

D)

Infinite resistance and normal inductance

Correct Answer : Infinite resistance and zero inductance

38 .

The coefficient of coupling between two air core coils depends on ____________

A)

Self inductance of two coils only

B)

Mutual inductance between two coils only

C)

Mutual inductance and a self inductance of two coils

D)

None of the above

Correct Answer : Mutual inductance and a self inductance of two coils

39 .

Electricity may be generated by a wire_________

A)

carrying current

B)

wrapped as a coil

C)

that has neutral domains

D)

passing through a flux field

Correct Answer : passing through a flux field

40 .

Which type of device consists of a coil with a moveable iron core?

A)

relay

B)

solenoid

C)

armature

D)

reed switch

Correct Answer : solenoid