ELECTROMAGNETIC INDUCTIONElectromagnetic Induction Multiple Choice Questions

1. The property of coil by which a counter e.m.f. is induced in it when the current through the coil changes is known as
1. self-inductance
2. mutual inductance
3. series aiding inductance
4. capacitance
As per Faraday’s laws of electromagnetic induction, an e.m.f. is induced in a conductor whenever it
1. lies perpendicular to the magnetic flux
2. lies in a magnetic field
3. cuts magnetic flux
4. moves parallel to the direction of the magnetic field
Which of the following circuit element stores energy in the electromagnetic field
1. Inductance
2. Condenser
3. (c) Variable resistor
4. Resistance
The inductance of a coil will increase under all the following conditions except
1. when more length for the same number of turns is provided
2. when the number of turns of the coil increase
3. when more area for each turn is provided
4. when permeability of the core increases
Higher the self-inductance of a coil,
1. lesser its weber-turns
2. lower the e.m.f. induced
3. greater the flux produced by it
4. longer the delay in establishing steady current through it
In an iron cored coil the iron core is removed so that the coil becomes an air cored coil. The inductance of the coil will
1. increase
2. decrease
3. remain the same
4. initially increase and then decrease
An open coil has
1. zero resistance and inductance
2. infinite resistance and zero inductance
3. infinite resistance and normal inductance
4. zero resistance and high inductance
Both the number of turns and the core length of an inductive coil are doubled.
Its self-inductance will be
1. unaffected
2. doubled
3. halved
4. quadrupled
If current in a conductor increases then according to Lenz’s law self-induced voltage will
1. aid the increasing current
2. tend to decrease the amount of cur-rent
3. produce current opposite to the in-creasing current
4. aid the applied voltage
The direction of induced e.m.f. can be found by
1. Laplace’s law
2. Lenz’s law
3. Fleming’s right hand rule
4. Kirchhoff s voltage law
Air-core coils are practically free from
1. hysteresis losses
2. eddy current losses
3. both (a) and (b)
4. none of the above
The magnitude of the induced e.m.f. in a conductor depends on the
1. flux density of the magnetic field
2. amount of flux cut
3. amount of flux linkages
4. rate of change of flux-linkages
Mutually inductance between two magnetically-coupled coils depends on
1. permeability of the core
2. the number of their turns
3. cross-sectional area of their common core
4. all of the above
. A laminated iron core has reduced eddy-current losses because
1. more wire can be used with less D.C. resistance in coil
2. the laminations are insulated from each other
3. the magnetic flux is concentrated in the air gap of the core
4. the laminations are stacked vertfcally
The law that the induced e.m.f. and current always oppose the cause producing them is due to
1. Faraday
2. lenz
3. newton
4. Coulomb
Which of the following is not a unit of inductance ?
1. Henry
2. Coulomb/volt ampere
3. Volt second per ampere
4. All of the above
In case of an inductance, current is proportional to
1. voltage across the inductance
2. magnetic field
3. both (a) and (b)
4. neither (a) nor (b)
Which of the following circuit elements will oppose the change in circuit current ?
1. Capacitance
2. Inductance
3. Resistance
4. All of the above
For a purely inductive circuit which of the following is true ?
1. Apparent power is zero
2. Relative power is.zero
3. Actual power of the circuit is zero
4. Any capacitance even if present in the circuit will not be charged
Which of the following is unit of inductance ?
1. Ohm
2. Henry
3. Ampere turns
4. Webers/metre

ELECTROMAGNETIC INDUCTION
Electromagnetic Induction Multiple Choice Questions

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