Electromagnetics Field (3140912) MCQs

MCQs of Magnetic forces, materials and inductance

Showing 121 to 130 out of 171 Questions
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121.
Both the number of turns and the core length of an inductive coil are doubled. Its self-inductance will be
(a) Unaffected
(b) Doubled
(c) Halved
(d) Quadrupled
Answer:

Option (b)

122.
If current in a conductor increases then according to Lenz's law self-induced voltage will
(a) Help the increasing current
(b) Tend to decrease the amount of current
(c) Produce current opposite to the increasing current
(d) Help the applied voltage
Answer:

Option (c)

123.
Air-core coils are practically free from
(a) Hysteresis losses
(b) Eddy current losses
(c) Both (a) and (b)
(d) None of above
Answer:

Option (c)

124.
The magnitude of the induced emf in a conductor depends on the
(a) Flux density of the magnetic field
(b) Amount of flux cut
(c) Amount of flux linkages
(d) Rate of change of flux linkages
Answer:

Option (d)

125.
Mutual inductance between two magnetically coupled coils depends on
(a) Permeability of the core
(b) Number of coil turns
(c) Cross sectional area of common core
(d) All of above
Answer:

Option (d)

126.
A laminated iron core has reduced eddy current losses because
(a) More conductor can be used with less DC resistance in coil
(b) Laminations are insulated from each other
(c) Magnetic flux is concentrated in the air gap of the core
(d) Laminations are stacked vertically
Answer:

Option (b)

127.
Which of the following is not a unit of inductance?
(a) Henry
(b) Coulomb/Volt-ampere
(c) Volt-second/Ampere
(d) All of above
Answer:

Option (b)

128.
In case of an inductance, current is proportional to
(a) Voltage across the inductance
(b) Magnetic field
(c) Both (a) and (b)
(d) Neither (a) nor (b)
Answer:

Option (b)

129.
The core of a coil has a length of 200 mm. The inductance of coil is 6 mH. If the core length is doubled, all other quantities, remaining the same, the inductance will be
(a) 3 mH
(b) 12 mH
(c) 24 mH
(d) 48 mH
Answer:

Option (a)

130.
An emf of 16 V is induced in a coil of inductance 4 H. The rate of change of current must be
(a) 64 A/Sec
(b) 32 A/Sec
(c) 16 A/Sec
(d) 4 A/Sec
Answer:

Option (d)

Showing 121 to 130 out of 171 Questions
10 11 12 13 14 15