Electromagnetic Induction  MCQs

MCQs of Electromagnetic Induction

Showing 61 to 70 out of 113 Questions
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61.
An electric motor operating at 200 V draws a current of 10 A at full speed. If armature resistance is 10 Ω, then efficiency of the motor is _____.
(a) 25%
(b) 50%
(c) 75%
(d) 100%
Answer:

Option (b)

62.
Eddy currents are produced in metallic plate, when it is _____.
(a) heated
(b) placed in a steady magnetic field
(c) placed in a steady electric field
(d) placed in a time varying magnetic field
Answer:

Option (d)

63.
An inductor may store energy in _____.
(a) a magnetic field
(b) an electric field
(c) Both (A) and (B)
(d) nothing can be said
Answer:

Option (a)

64.
The self-inductance of a solenoid is _____.
(a) directly proportional to the current
(b) directly proportional to length
(c) directly proportional to its cross sectional area
(d) inversely proportional to its area of cross section
Answer:

Option (c)

65.
A horizontal metallic wire, whose length is along east-west falls under gravity. Potential difference (emf) across the ends will _____.
(a) increase with time
(b) decrease with time
(c) zero
(d) remain constant
Answer:

Option (a)

66.
A coil of self inductance 0.5 mH carries a current of 2 A. The energy stored is _____ mJ.
(a) 0.5
(b) 0.05
(c) 1.0
(d) 0.1
Answer:

Option (c)

67.
A magnetic field in a certain region is given by B→=40i∧ - 18k∧ G. How much flux passes through a 5.0 cm2 area of the loop, if the loop lies flat on the XY plane ? IG (gauss) = 10-4 T .
(a) -900 nWb
(b) -9 nWb
(c) zero
(d) 90 nWb
Answer:

Option (a)

68.
A helicopter is moving in upward direction with speed of 10 m/s. If the length of helicopter is 10 m and the horizontal component of magnetic field of earth is 1.5 × 10-3wbm2 then the induced emf produced across the foremost (nose) and end part (tail) of the helicopter will be _____
(a) 0.15 V
(b) 125 V
(c) 130 V
(d) 5 V
Answer:

Option (a)

69.
The current passing through a chock coil of 5H is decreasing at the rate of 2As . The emf developed across the coil is _____
(a) -10 V
(b) 10 V
(c) 2.5 V
(d) -2.5 V
Answer:

Option (b)

70.
An emf of 5V is produced in a coil when current changes at a steady rate from 3A to 2A in 1 ms. The value of self-inductance is _____
(a) 5 × 102 H
(b) 5 × 100 H
(c) 5 × 10-3 H
(d) 0.005mH
Answer:

Option (c)

Showing 61 to 70 out of 113 Questions
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