Chapter 4: Electromagnetism Physics Mcqs for High School - Grade 10 - Set 4

1)   As per Faraday's law of electromagnetic induction, the value of induced electromotive force in a circuit is directly proportional to the rate of change of the number of

a. potential difference
b. electromagnetic difference
c. magnetic lines of force
d. electromagnetic induction
Answer  Explanation 

ANSWER: magnetic lines of force

Explanation:
No explanation is available for this question!


2)   The direction of induced current always

a. opposes the cause
b. remains same as that of cause
c. equal to cause that produces it
d. directs the cause
Answer  Explanation 

ANSWER: opposes the cause

Explanation:
No explanation is available for this question!


3)   If a coil is rotated in a magnetic field, there will be induced a

a. current
b. wave
c. friction
d. stress
Answer  Explanation 

ANSWER: current

Explanation:
No explanation is available for this question!


4)   Soft iron can be easily

a. magnetized only
b. demagnetized only
c. convert into gas
d. magnetized and demagnetized
Answer  Explanation 

ANSWER: magnetized and demagnetized

Explanation:
No explanation is available for this question!


5)   The direction of the magnetic field is governed by the direction of

a. voltage
b. Electromotive force (EMF)
c. current
d. none of above
Answer  Explanation 

ANSWER: current

Explanation:
No explanation is available for this question!


6)   An electromagnet is

a. permanent
b. temporary
c. insulator
d. conductor
Answer  Explanation 

ANSWER: temporary

Explanation:
No explanation is available for this question!


7)   When the plane of the coil is parallel to the lines of magnetic force, the number of lines of magnetic force passing through the coil will be

a. minimum
b. maximum
c. zero
d. none of above
Answer  Explanation 

ANSWER: zero

Explanation:
No explanation is available for this question!


8)   In coil, the change in the number of magnetic field lines will induce an

a. electromotive force
b. potential difference
c. electromagnetic force
d. none of above
Answer  Explanation 

ANSWER: electromotive force

Explanation:
No explanation is available for this question!


9)   The power is transmitted over long distances and high voltages to

a. minimize the energy loss
b. maximize the energy loss
c. make energy content constant
d. preserve energy
Answer  Explanation 

ANSWER: minimize the energy loss

Explanation:
No explanation is available for this question!


10)   To increase or decrease AC voltages, we use

a. fuse
b. circuit breaker
c. transformer
d. generator
Answer  Explanation 

ANSWER: transformer

Explanation:
No explanation is available for this question!


11)   The magnitude of induced e.m.f in a circuit depends on the

a. speed of relative motion of coil
b. speed of relative motion of magnet
c. number of turns of the coil
d. all of above
Answer  Explanation 

ANSWER: all of above

Explanation:
No explanation is available for this question!


12)   The value of induced Electromotive force (EMF) is directly proportional to

a. current through coil
b. voltage applied
c. no. of field lines
d. resistivity
Answer  Explanation 

ANSWER: no. of field lines

Explanation:
No explanation is available for this question!


13)   When the surface is held parallel to the magnetic lines of force, the number of lines of force is

a. negative
b. zero
c. maximum
d. minimum
Answer  Explanation 

ANSWER: minimum

Explanation:
No explanation is available for this question!


14)   The number of magnetic lines of force passing through any surface is called

a. nature of magnetic field
b. strength of magnetic field
c. work of magnetic field
d. weakness of magnetic field
Answer  Explanation 

ANSWER: strength of magnetic field

Explanation:
No explanation is available for this question!


15)   If the secondary voltage is smaller than the primary voltage, the transformer is called a

a. positive transformer
b. step-up transformer
c. negative transformer
d. step-down transformer
Answer  Explanation 

ANSWER: step-down transformer

Explanation:
No explanation is available for this question!


16)   A device that converts electric energy into rotational kinetic energy is called

a. circuit breaker
b. transformer
c. generator
d. electric motor
Answer  Explanation 

ANSWER: electric motor

Explanation:
No explanation is available for this question!


17)   The loop in magnetic field rotates due to

a. Electromotive force (EMF)
b. frequency
c. resistance
d. torque
Answer  Explanation 

ANSWER: torque

Explanation:
No explanation is available for this question!


18)   If the coil is placed perpendicular to field lines then the number of lines passing through the coil is

a. minimum
b. maximum
c. zero
d. may be max. or min.
Answer  Explanation 

ANSWER: maximum

Explanation:
No explanation is available for this question!


19)   If a transformer is used to supply voltage to a 15 V model train which draws a current of 0.7 A. If the voltage of the A.C source is 210 V, the current in the primary should be

a. 0.04 A
b. 0.05 A
c. 0.03 A
d. 0.02 A
Answer  Explanation 

ANSWER: 0.05 A

Explanation:
No explanation is available for this question!


20)   If the AC source is 240 V and a transformer supplies 12 V to a model train which draws a current of 0.8 A then primary current is

a. 0.4 A
b. 0.04 A
c. 0.0416666666666667
d. 0.0833333333333333
Answer  Explanation 

ANSWER: 0.04 A

Explanation:
No explanation is available for this question!