# ELECTRICITY AND MAGNETISM Mcqs

1.Electro motive force is most closely related to

a. Electric field

b. Potential difference

c. Mechanical force

d. Magnetic field

2.A transformer works with

a. Any signal

b. Alternating current

c. Direct current

d. Both AC and DC

3.Faraday’s law of electromagnetic induction is related to the

a. none

b. Law of conservation of energy

c. Law of conservation of charge

d. Third law of motion

4.An example for diamagnetic substance is

a. Nickel

b. Copper

c. Aluminium

d. Iron

5.The force that appears at a result of the interaction between two moving charges is called

a. Magnetic Force

b. Induced Force

c. Gravitational Force

d. Electrostatic Force

6.The magnetic field lasts only as long as ____ flowing through the conductor

a. Current

b. Voltage

c. emf

d. none

7.The direction of magnetic field due to current carrying conductor can be determined by

a. left Hand Rule

b. Fleming’s Right Hand Rule

c. Palm Right Hand Rule

d. Right Hand Rule

8.The SI unit of magnetic field strength

a. Ampere

b. Weber

c. Tesla

d. Henry

9.The direction of induced current is always so as to oppose the change which causes the current is called:

b. Ohm’s law

c. Kirchhoff’s 1st rule

d. Lenz’s law

10.The SI units of induced emf is

a. Tesla

b. Henry

c. Volt

d. Ohm

11.The mean value of A.C. over a complete cycle in

a. Zero

b. Minimum

c. Maximum

d. None

12.At high frequency, the current through a capacitor of AC circuit will be:

a. infinity

b. Large

c. Small

d. Zero

13.The highest value reached by the voltage or current in one cycle is called

a. Peak to peak value

b. Root mean square value

c. Instantaneous value

d. Peak value

14.To construct a step down transformer:

a. 𝑁𝑆 =𝑁𝑃

b. 𝑁𝑆.𝑁𝑃 =1

c. 𝑁𝑆 <𝑁𝑃

d. 𝑁𝑃 <𝑁𝑆

15.Power dissipation in pure inductive or in a pure capacitive circuit is: a) Infinite

a. infinity

b. Minimum

c. Maximum

d. Zero

16.The r.m.s. value of A.C current in

a. 0.707 Io

b. 0.707 Vo

c. 0.707 Ro

d. None

17.A device that allows permits flow of DC through the circuit easily, is called:

a. AC generator

b. Inductor

c. Capacitor

d. Transformer

18.The unit used for capacitive reactance is

a. Ampere

b. Joule

c. ohm

d. Volt

19.In case of capacitor, the voltage lag behind the current by

a. 60

b. 30

c. 180

d. 90

20.If the frequency of A.C. is doubled, the reactance of inductor will be

a. Same

b. Triple

c. half

d. Double

21.At resonance frequency the power factor is

a. Three

b. One

c. Zero

d. Two

22.The condition of resonance reached when

a. XC > XL

b. XL < XC

c. none

d. XL = XC

23.In RLC series AC circuit, when XL = XC then impedance is

a. Z=XL

b. Z=XC

c. Z=infinity

d. Z=R

24.The combine opposition of resistor, capacitor and inductor is called

a. Resistor

b. Reactance

c. None

d. Impedance

25.The Phenomenon by  which an induced emf is produced in the conductor due to change of magnetic flux in it is called:

a. Electromagnetic induction

b. Electro magnetism

c. Electric polarization

d. All of above

26.The unit of induced emf is:

a. Henary

b. Ampere

c. Joule/coulomb

d. V/m

27.The rate of change of magnetic flux is directly proportional to the induced emf is called:

b. Lenz law

c. Oersted law

d. None of them

28.Energy stored per unit volume inside a long solenoid is known as:

a. Surface charge density

b. Energy density

c. Energy

d. Power density

29.The SI unit of mutual inductance is:

a. Coulomb

b. Ampere

c. Henry

30.Which of the following is scalar:

a. magnetic field

b. pointing vector

c. Flux density

d. electric fiels

31.A 50 mH coil carries a current of 2A. The energy stored in its magnetic field is:

a. E = 50 J

b. E = 0.1 J

c. E = 005 J

d. E = 10J

32.A.C is converted into D.C by:

a. Transformer

b. Rectifier

c. Dynamo

d. Motor

33.The direction of the induced emf during electromagnetic induction can be determined by the use of:

a. Amperes law

b. Coulomb’s law

d. Lenz’s law

34.1 Henry =

a. VSA-2

b. VSA-1

c. VS-1A-1

d. V-1SA

35.The basic circuit element in a D.C circuit is:

a. An inductor

b. A capacitor

c. None of these

d. A resistor

36.In a resistive A.C circuit, instantaneous values of voltage and current are:

b. Out of phase

c. None of these

d. In phase

37.When voltage V and current I are in phase the power is expressed as:

a. P = VR

b. P = VI cos θ

c. P = I2R

d. P = VI sin θ

38.With high frequencies, capacitive reactance:

a. Increases

b. None

c. Decreases

d. Remain unchanged

39.For parallel resonant circuit, the resonance current is:

a. maximum

b. zero

c. infinity

d. Minimum

40.The impedance of pure anti-resonant which at resonance is:

a. infinity

b. 1

c. 0

d. 50 ohm

41.The peak value of alternating voltage is 423 volts, its rms value is:

a. 300 volts

b. 150 volts

c. 423 volts

d. 211.5 volts

42.A capacitor of capacitance 30 mF is charged by a constant current of 10 mA. If initially capacitor is uncharged, what is time taken for potential difference across capacitor to reach 300 V?

a. 180sec

b. 0.9 sec

c. 15sec

d. 30min

43.Who proved that light waves are electromagnetic?

a. Enderson

c. Maxwell

d. Einstein

44.The waveform of alternating voltage is a:

a. Rectangular

b. None of these

c. Sinusoidal

d. Square

45.Alternating current can be produced by:

a. Electric motor

b. Generator

c. Turbine

d. Transformer

46.Power factor is defined by:

a. sin q

b. sec q

c. tan q

d. cos q

47.The reciprocal of impedance is called:

a. Capacitance

b. Resistance

d. Inductance

48.A 100 mF capacitor will offer a reactance of:

a. 90 W

b. 32 W

c. 60 W

d. 42 W

49.The electromagnetic spectrum contains:

b. Microwaves

c. X-rays

d. All of these

50.For q – t graph, slope shows:

a. none

b. current

c. voltage

d. emf