Electromagnetic Induction Mcqs – (Electrical Engineering) MCQs Latest For FPSC, PPSC, NTS, KPPSC, SPSC & Other Tests
“ Electromagnetic Induction Mcqs “. Tab this page to check “Latest Electromagnetic Induction MCQs” for the preparation of competitive mcqs, FPSC mcqs, PPSC mcqs, SPSC mcqs, KPPSC mcqs, AJKPSC mcqs, BPSC mcqs, NTS mcqs, PTS mcqs, OTS mcqs, Atomic Energy mcqs, Pak Army mcqs, Pak Navy mcqs, CTS mcqs, ETEA mcqs and others. The most occurred mcqs of Electromagnetic Induction in past papers. Past papers of Electromagnetic Induction mcqs. Past papers of Electromagnetic Induction MCQs. Mcqs are the necessary part of any competitive / job related exams. The Electromagnetic Induction mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related Electromagnetic Induction mcqs. The Important series of Electromagnetic Induction Mcqs are given below:
A coil of wire is arranged with its plane perpendicular to a uniform magnetic field o flux density B. when the radius of the coil increases from r1 to r2 in time Δt then what is the emf induced in the coil ?
A. ωB(r2-r1)2/Δt
B. ωB/r22-r12/Δt
C. ωB(r22-r12)/Δt
D. ωB(r22+r12)/Δt
Self-inductance of a long solenoid is______________?
A. μoN2A
B. μoN2
C. μoN2/A
D. BA
The alternating current has frequency of 106 Hz in such a way that time period for completion of cycle is_______________?
A. 1Hzs
B. 106sec
C. 1.5Hzs
D. 1sec
Self inductance of a coil depends upon________________?
A. number of turns per unit length
B. current flowing
C. voltage produce
D. all
Energy stored in a magnetic field is given by______________?
A. L2I/2
B. LI2
C. LI2/2
D. IL2
For electroplating we use_________________?
A. A D.C source
B. an A.C source
C. None of the above
D. all of the above
The only difference between construction of D.C generator and A.C generator is that of_______________?
A. coil
B. carbon brushes
C. commutator
D. magnetic field
If the secondary coil has Ns turns and the primary Np turns the relation between secondary and primary voltages is given by_____________?
A. Vp/Vs = Ns/Np
B. Vs/Vp = Ns/Np
C. Vs/Vp = Np/Ns
D. Vp/Vs = Np/Ns
A metal rod of 25 cm length is moving at a speed of 0.5/sec in direction perpendicular to 0.25T magnetic field. Emf produced in the rod is_____________?
A. 3.125 volt
B. 0 volt
C. 31.25 volt
D. 0.03125 volt
The self-inductance of a solenoid is increased when a soft iron core is inserted into it. This is because the soft iron core_______________?
A. Reduces the effect of eddy current
B. Decreases the resistance of the solenoid
C. Improves the flux linkage between the turns of the coil
D. Increases the mutual inductance between the solenoid and the core
An aeroplane of wingspan 10m flies from the equator towards the North Pole. The wings are perpendicular to the vertical component of the earths magnetic field (B = 4×10-5T). At maximum speed an emf of 96mV is induced across the wing tips. The maximum speed of the aeroplane is____________?
A. 38.4msec-1
B. 384msec-1
C. 150msec-1
D. 200msec-1
Non inductive resistances are used in decreasing______________?
A. Magnetic fields
B. Self inductance
C. Mutual inductance
D. Heating effect
Which one of the following devices does not function like an electric motor ?
A. Ammeter
B. Galvanometer
C. Voltmeter
D. Transformer
For long distance transmission the transformer used is_____________?
A. Amplifier is used
B. Input voltage and output voltage remain same
C. Step up
D. Step down
Lagging of changes in the magnetization of a substance behind changes in the magnetic field as the magnetic field is varied is known as magnetic_____________?
A. Permeability
B. Retaintivity
C. Flux
D. Hysteresis
When the motor is at its maximum speed then back emf will be______________?
A. Maximum
B. Intermediate values
C. Zero
D. No back emf
Transformer works on the principle of________________?
A. Faradays law
B. Lenzs law
C. Mutual induction
D. Law of conservation of power
An electric current induced within the body of a conductor when that conductor either moves through a non uniform magnetic field or in a region where there is a change in magnetic flux is called_____________?
A. Back emf
B. Eddy current
C. Induced current
D. None of the above
The out put voltage of a transformer is 3 times the input voltage then turns ratio will be________________?
A. 1
B. 3
C. 3-Jan
D. 6
Long distance transmission is easy for________________?
A. Half A.C voltage
B. A.C voltage
C. D.C voltage
D. Half D.C voltage
Magnetic compass needle will be deflecting if it is kept near________________?
A. Soft iron
B. Static charge
C. Semi-conductor
D. Accelerating charge
A.C can not be used for_______________?
A. producing light
B. producing heat
C. Magnetizing iron
D. Producing magnetic field
A small coil lies inside a large coil. The two coils are horizontal concentric and carry currents in opposite directions. The large coil will experience______________?
A. A torque about vertical axis
B. A torque about horizontal axis
C. An upward force along the axis
D. No resultant force
The emf induced in a conductor of unit length moving with unit velocity at right angles to a magnetic field is equal to_____________?
A. Magnetic flux density
B. Mutual induction
C. Torque
D. Motional emf
The emf induced in a coil by a changing magnetic flux may have unit as______________?
A. ms-2A-1
B. ms-1A
C. kgms2A-1
D. kgm2s-1A-1
Power loss in actual transformer is due to_________________?
A. Soft iron core
B. Eddy currents and magnetic hysterias
C. Small output
D. Back emf
A.C and D.C have the same______________?
A. effect in charging a battery
B. effect in charging a capacitor
C. effect while passing through an inductance
D. heating effect through a resistance
Which of the following uses electric energy and does not convert it into any other form ?
A. transformer
B. D.C generator
C. motor
D. A.C generator
Inductors acts as a short circuit for_______________?
A. AC
B. DC
C. Both
D. none
If the coil is wound on an iron core the flux through it will_______________?
A. become zero
B. decrease
C. remain the same
D. increase
Which of the following works on torque on the current carrying conductor placed in magnetic field ?
A. ammeter
B. galvanometer
C. voltmeter
D. all of the above
A.C cannot be used for________________?
A. producing light
B. producing heat
C. magnetizing and electroplating
D. all the above
Which one of the following functions like a motor ?
A. ammeter
B. galvanometer
C. voltmeter
D. all of above
An alternating current or voltage________________?
A. fluctuates off and on
B. changes its direction again and again
C. varies in magnitude alone
D. changes its magnitude continuously and reverses its direction of flow after regularly recurring intervals.
emf induced in a circuit according to Faradays law depends on the_____________?
A. change in magnetic flux
B. rate of change of magnetic flux
C. maximum magnetic flux
D. initial magnetic flux
Weber is the unit of_____________?
A. magnetic induction
B. Magnetic field intensity
C. magnetic flux
D. self-inductance
A.C cannot be used for_______________?
A. producing light
B. producing heat
C. magnetizing and electroplating
D. all the above
A dynamo converts______________?
A. mechanical energy into electrical energy
B. magnetic energy into mechanical energy
C. electrical energy into mechanical energy
D. magnetic energy into electrical energy
cmf generated by A.C dynamo depends upon_____________?
A. magnetic field strength
B. number of turns in the coil
C. frequency of rotation
D. all of above
Current produced by moving the loop of wire across a magnetic field is called_____________?
A. D.C current
B. A.C current
C. induced current
D. mean square current
The practical illustration of the phenomenon of mutual induction is____________?
A. D.C dynamo
B. A.C generator
C. induction coil
D. transformer
The polarity of the induced voltage can be determined by using the left-hand generator rule
A. Yes
B. No
Reversing the field or the current will reverse the force on the conductor
A. Yes
B. No
The self-inductance of the coil may be defined as equal to the e.m.f. induced in volts when the current in the circuit changes at the rate of unit Weber turns
A. Yes
B. No
Which circuit element(s) will oppose the change in circuit current ?
A. Capacitance only
B. Inductance only
C. Resistance only
D. Inductance and capacitance
A coil is wound on iron core which carries current I. The self-induced voltage in the coil is not affected by________________?
A. change of number of turns of coil
B. variation in voltage to the coil
C. variation in coil current
D. the resistance of magnetic path
A crack in the magnetic path of an inductor will result in________________?
A. increased inductance
B. unchanged inductance
C. zero inductance
D. reduced inductance
The co-efficient of coupling between two air core coils depends on____________?
A. mutual inductance between two coils only
B. self-inductance of two coils only
C. mutual inductance and self inductance of two coils
D. none of the above
Current changing from 8 A to 12 A in one second induced 20 volts in a coil. The value of inductance is___________?
A. 10 mH
B. 5 mH
C. 5 H
D. 10 H
A coil induces 350 mV when the current changes at the rate of 1 A/s. The value of inductance is___________?
A. 250 mH
B. 350 mH
C. 3500 mH
D. 150 mH
Find the force acting on a conductor 3m long carrying a current of 50 amperes at right angles to a magnetic field having a flux density of 0.67 tesla
A. 100 N
B. 600 N
C. 400 N
D. 1000 N
An average voltage of 10 V is induced in a 250 turns solenoid as a result of a change in flux which occurs in 0.5 second. The total flux change is____________?
A. 2 Wb
B. 20 Wb
C. 0.2 Wb
D. 0.02 Wb
Two 300 uH coils in series without mutual coupling have a total inductance of___________?
A. 300 uH
B. 150 uH
C. 600 uH
D. 75 uH
Which of the fpllowing inductor will have the least eddy current losses ?
A. Air core
B. Iron core
C. Laminated iron core
D. Powdered iron core
A 500 turns solenoid develops an average induced voltage of 60 V. Over what time interval must a flux change of 0.06 Wb occur to produce such a voltage ?
A. 0.1 s
B. 0.01 s
C. 0.5 s
D. 5 s
A coil with negligible resistance has 50V across it with 10 mA. The inductive reactance is_____________?
A. 500 ohms
B. 50 ohms
C. 1000 ohms
D. 5000 ohms
A conductor carries 125 amperes of current under 60° to a magnetic field of 1.1 tesla. The force on the conductor will be nearly______________?
A. 240 N
B. 120 N
C. 50 N
D. 480 N
A conductor 2 meters long moves at right angles to a magnetic field of flux density 1 tesla with a velocity of 12.5 m/s. The induced e.m.f. in the conductor will be____________?
A. 15 V
B. 10 V
C. 25V
D. 50V
Two coils have self-inductances of 10 H and 2 H, the mutual inductance being zero. If the two coils are connected in series, the total inductance will be_____________?
A. 8 H
B. 6 H
C. 12 H
D. 24 H
Lenz’s law is a consequence of the law of conservation of__________?
A. charge
B. induced current
C. energy
D. induced e.m.f.
In case all the flux from the current in coil 1 links with coil 2, the co-efficient of coupling will be____________?
A. 0.5
B. 1.0
C. 2.0
D. zero
A 200 turn coil has an inductance of 12 mH. If the number of turns is increased to 400 turns, all other quantities (area, length etc.) remaining the same, the inductance will be___________?
A. 14 mH
B. 6 mH
C. 24 mH
D. 48 mH
The self inductances of two coils are 8 mH and 18 mH. If the co-efficients of coupling is 0.5, the mutual inductance of the coils is______________?
A. 5 mH
B. 4 mH
C. 6 mH
D. 12 mH
In case of an inductance, current is proportional to___________?
A. voltage across the inductance
B. magnetic field
C. both of the above
D. neither of the above
For a purely inductive circuit which of the following is true ?
A. Relative power is zero
B. Apparent power is zero
C. Actual power of the circuit is zero
D. Any capacitance even if present in the circuit will not be charged
An e.m.f. of 16 volts is induced in a coil of inductance 4H. The rate of change of current must be______________?
A. 32 A/s
B. 64 A/s
C. 16 A/s
D. 4 A/s
Two coils have inductances of 8 mH and 18 mH and a co-efficient of coupling of 0.5. If the two coils are connected in series aiding, the total inductance will be______________?
A. 40 mH
B. 38 mH
C. 32 mH
D. 48 mH
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. 24 mH
C. 12 mH
D. 48 mH
Which of the following is unit of inductance ?
A. Ampere turns
B. Henry
C. Ohm
D. Webers/metre
Which of the following circuit elements will oppose the change in circuit current ?
A. Resistance
B. Inductance
C. Capacitance
D. All of the above
A laminated iron core has reduced eddy-current losses because____________?
A. the laminations are stacked vertically
B. the laminations are insulated from each other
C. the magnetic flux is concentrated in the air gap of the core
D. more wire can be used with less D.C. resistance in coil
The magnitude of the induced e.m.f. in a conductor depends on the______________?
A. flux density of the magnetic field
B. amount of flux linkages
C. amount of flux cut
D. rate of change of flux-linkages
Which of the following is not a unit of inductance ?
A. Volt second per ampere
B. Coulomb/volt ampere
C. Henry
D. All of the above
Mutually inductance between two magnetically-coupled coils depends on____________?
A. the number of their turns
B. permeability of the core
C. cross-sectional area of their common core
D. all of the above
The law that the induced e.m.f. and current always oppose the cause producing them is due to____________?
A. Newton
B. Lenz
C. Faraday
D. Coulomb
If current in a conductor increases then according to Lenz’s law self-induced voltage will____________?
A. aid the applied voltage
B. tend to decrease the amount of cur-rent
C. produce current opposite to the in-creasing current
D. aid the increasing current
Air-core coils are practically free from______________?
A. hysteresis losses
B. eddy current losses
C. both of the above
D. none of the above
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__________?
A. self-inductance
B. capacitance
C. series aiding inductance
D. mutual inductance
The direction of induced e.m.f. can be found by_____________?
A. Fleming’s right hand rule
B. Lenz’s law
C. Laplace’s law
D. Kirchhoff s voltage law
An open coil has_____________?
A. zero resistance and high inductance
B. infinite resistance and zero inductance
C. infinite resistance and normal inductance
D. zero resistance and inductance
The inductance of a coil will increase under all the following conditions except______________?
A. when more length for the same number of turns is provided
B. when more area for each turn is provided
C. when the number of turns of the coil increase
D. when permeability of the core increases
As per Faraday’s laws of electromagnetic induction, an e.m.f. is induced in a conductor whenever it_______________?
A. lies in a magnetic field
B. lies perpendicular to the magnetic flux
C. cuts magnetic flux
D. moves parallel to the direction of the magnetic field
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_____________?
A. remain the same
B. decrease
C. increase
D. initially increase and then decrease
Both the number of turns and the core length of an inductive coil are doubled. Its self-inductance will be_____________?
A. halved
B. doubled
C. unaffected
D. quadrupled
Higher the self-inductance of a coil_____________?
A. lower the e.m.f. induced
B. lesser its weber-turns
C. greater the flux produced by it
D. longer the delay in establishing steady current through it
Which of the following circuit element stores energy in the electromagnetic field ?
A. Inductance
B. Variable resistor
C. Condenser
D. Resistance