40 Important Electromagnetic induction MCQ Question and Answer | PDF Free Download
1.The property of coil by which a counter EMF is induced in it. when the current through the coil changes is known as
- ASelf-inductance
- BMutual inductance
- CSeries aiding inductance
- DCapacitance
2.As per faraday?s law of electromagnetic induction, an EMF is induced in a conductor whenever it
- ALies perpendicular to magnetic flux
- BLies in a magnetic line
- CCuts the magnetic flux
- DMoves parallel to the direction of the magnetic field
3.Which of the following circuit elements stores energy in the electromagnetic field?
- AInductance
- BCondenser
- CVariable resistor
- DResistance
4.The inductance of a coil will increase under all the following conditions excepts
- AWhen more length for the same number of turns is provided
- BWhen the number of turns of the coil increase
- CWhen more area for each turn is provided
- DWhen permeability of the core increases
5.Higher the self-inductance of the coil
- ALesser its Webber-turns
- BLower the e.m.f induced
- CGreater the flux produced by it
- DLonger the delay in establishing steady current through it
6.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
- AIncrease
- BDecrease
- CRemain same
- DInitially increase then decrease
7.An open coil has
- AZero resistance and inductance
- BInfinite resistance and Zero inductance
- CInfinite resistance and normal inductance
- DZero resistance and high inductance
8.Both the number of turn and core length of an inductive coil are doubled. Its self-inductance will be
- AUnaffected
- BDoubled
- CHalved
- DQuadrupled
9.If current in a conductor increases then according to Lenz?s law self-inductance voltage will
- AAid the increasing current
- BTends to decrease the amount of current
- CProduce current opposite to the increasing current
- DAid the applied voltage
10.The direction of induced e.m.f can be found by
- ALaplace?s law
- BLenz?s law
- CFleming?s right-hand rule
- DKirchhoff?s voltage law
11.Air-core coils are practically free from
- A hysteresis losses
- BEddy current losses
- CBoth (a) and (b)
- DNone of the above
12.The magnitude of the induced EMF in a conductor depends on the
- AFlux density of the magnetic field
- BRate of change of flux-linkages
- CAmount of flux cut
- DAmount of flux linkages
13.Mutually inductance between two magnetically-coupled coils depends upon
- APermeability of the core
- BThe number of their turns
- CCross-sectional area of their common core
- DAll of the above
14.A laminated iron core has reduced eddy-current losses because
- AMore wire can be used with less D.C resistance in coil
- BThe laminations are insulated from each other
- CThe magnetic flux is concentrated in the air gap of the core
- DThe laminations are stacked vertically
15.The law that the induced e.m.f and current always oppose the cause which produced it, is discovered by
- AFaraday?s
- BLenz
- CNewton
- DCoulomb
16.Which of the following is not a unit of inductance?
- AHennery
- BCoulomb/volt ampere
- CVolt second/ampere
- DAll of the above
17.In case of an inductance, current is proportional to
- AVoltage across the inductance
- BMagnetic field
- CNeither (a) nor (b)
- DBoth (a) and (b)
18.For a purely inductive circuit which of the following ids true?
- AApparent power is zero
- BRelative power is zero
- CActual power of the circuit is zero
- DAny capacitance even if present in the circuit will not be charged
19.The unit of inductance is
- AOhm
- BHenry
- CAmpere turns
- DWeber/meters
20.An e.m.f of 16 volts is induced in a coil of inductance 4H. the rate of change of current must be
- A64A/s
- B32 A/s
- C16 A/s
- D4 a/s