-
question_answer1)
In electromagnetic induction, the induced e.m.f. in a coil is independent of [CPMT 1984]
A)
Change in the flux done
clear
B)
Time done
clear
C)
Resistance of the circuit done
clear
D)
None of the above done
clear
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question_answer2)
Lenz's law is consequence of the law of conservation of [JIPMER 1997; CPMT 1990; RPMT 1997; MP PET 1999; MP PMT 2000, 03; RPET 2003; AFMC 2004]
A)
Charge done
clear
B)
Momentum done
clear
C)
Mass done
clear
D)
Energy done
clear
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question_answer3)
In electromagnetic induction, the induced charge in a coil is independent of
A)
Change in the flux done
clear
B)
Time done
clear
C)
Resistance in the circuit done
clear
D)
None of the above done
clear
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question_answer4)
The magnetic flux through a circuit of resistance \[R\] changes by an amount \[\Delta \varphi \] in time \[\Delta t\], Then the total quantity of electric charge \[Q\], which passing during this time through any point of the circuit is given by [Haryana CEE 1996; CBSE PMT 2004]
A)
\[Q=\frac{\Delta \varphi }{\Delta t}\] done
clear
B)
\[Q=\frac{\Delta \varphi }{\Delta t}\times R\] done
clear
C)
\[Q=-\frac{\Delta \varphi }{\Delta t}+R\] done
clear
D)
\[Q=\frac{\Delta \varphi }{R}\] done
clear
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question_answer5)
A cylindrical bar magnet is kept along the axis of a circular coil. If the magnet is rotated about its axis, then [CPMT 1983; BCECE 2004]
A)
A current will be induced in a coil done
clear
B)
No current will be induced in a coil done
clear
C)
Only an e.m.f. will be induced in the coil done
clear
D)
An e.m.f. and a current both will be induced in the coil done
clear
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question_answer6)
A metallic ring is attached with the wall of a room. When the north pole of a magnet is brought near to it, the induced current in the ring will be [AFMC 1993; MP PMT/PET 1998; Pb PET 2003]
A)
First clockwise then anticlockwise done
clear
B)
In clockwise direction done
clear
C)
In anticlockwise direction done
clear
D)
First anticlockwise then clockwise done
clear
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question_answer7)
A coil having an area \[{{A}_{0}}\] is placed in a magnetic field which changes from \[{{B}_{0}}\]to \[4{{B}_{0}}\] in a time interval t. The e.m.f. induced in the coil will be [MP PET 1990]
A)
\[\frac{3{{A}_{0}}{{B}_{0}}}{t}\] done
clear
B)
\[\frac{4{{A}_{0}}{{B}_{0}}}{t}\] done
clear
C)
\[\frac{3{{B}_{0}}}{{{A}_{0}}t}\] done
clear
D)
\[\frac{4{{B}_{0}}}{{{A}_{0}}t}\] done
clear
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question_answer8)
The magnetic flux linked with a coil is given by an equation \[\varphi \] (in webers) = \[8{{t}^{2}}+3t+5\]. The induced e.m.f. in the coil at the fourth second will be [MP PET 1990]
A)
16 units done
clear
B)
39 units done
clear
C)
67 units done
clear
D)
145 units done
clear
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question_answer9)
The current flowing in two coaxial coils in the same direction. On increasing the distance between the two, the electric current will [MP PMT 1991]
A)
Increase done
clear
B)
Decrease done
clear
C)
Remain unchanged done
clear
D)
The information is incomplete done
clear
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question_answer10)
A copper ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet while it is passing through the ring is [CBSE PMT 1996; MP PET 1990, 99; CPMT 1991, 99; JIPMER 1997; CPMT 2003; MP PET/PMT 2001; KCET 2001; Kerala (Engg.) 2001]
A)
Equal to that due to gravity done
clear
B)
Less than that due to gravity done
clear
C)
More than that due to gravity done
clear
D)
Depends on the diameter of the ring and the length of the magnet done
clear
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question_answer11)
A square coil \[{{10}^{-2}}{{m}^{2}}\] area is placed perpendicular to a uniform magnetic field of intensity \[{{10}^{3}}Wb/{{m}^{2}}\]. The magnetic flux through the coil is [MP PMT 1990, 2001]
A)
10 weber done
clear
B)
\[{{10}^{-5}}\]weber done
clear
C)
\[{{10}^{5}}\]weber done
clear
D)
100 weber done
clear
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question_answer12)
A magnet is brought towards a coil (i) speedly (ii) slowly then the induced e.m.f./induced charge will be respectively [RPMT 1997; MP PMT 2003]
A)
More in first case / More in first case done
clear
B)
More in first case/Equal in both case done
clear
C)
Less in first case/More in second case done
clear
D)
Less in first case/Equal in both case done
clear
View Solution play_arrow
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question_answer13)
The direction of induced e.m.f. during electromagnetic induction is given by [MP PET 1994, 96]
A)
Faraday's law done
clear
B)
Lenz's law done
clear
C)
Maxwell's law done
clear
D)
Ampere's law done
clear
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question_answer14)
In a coil of area \[10\ c{{m}^{2}}\] and 10 turns with a magnetic field directed perpendicular to the plane and is changing at the rate of \[{{10}^{8}}\]gauss/second. The resistance of the coil is 20 ohm. The current in the coil will be [CPMT 1976]
A)
5 amp done
clear
B)
0.5 amp done
clear
C)
0.05 amp done
clear
D)
\[5\times {{10}^{8}}\ amp\] done
clear
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question_answer15)
As shown in the figure, a magnet is moved with a fast speed towards a coil at rest. Due to this induced electromotive force, induced current and induced charge in the coil is \[E,\ I\] and \[Q\] respectively. If the speed of the magnet is doubled, the incorrect statement is [MP PET 1995]
A)
\[E\] increases done
clear
B)
\[I\] increases done
clear
C)
\[Q\] remains same done
clear
D)
\[Q\] increases done
clear
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question_answer16)
A coil having 500 square loops each of side 10 cm is placed normal to a magnetic flux which increases at the rate of 1.0 tesla/second. The induced e.m.f. in volts is [CPMT 1989, 90; DCE 2002]
A)
0.1 done
clear
B)
0.5 done
clear
C)
1 done
clear
D)
5 done
clear
View Solution play_arrow
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question_answer17)
When a magnet is pushed in and out of a circular coil C connected to a very sensitive galvanometer G as shown in the adjoining diagram with a frequency \[\nu \], then
A)
Constant deflection is observed in the galvanometer done
clear
B)
Visible small oscillations will be observed in the galvanometer if \[\nu \]is about 50 Hz done
clear
C)
Oscillations in the deflection will be observed clearly if \[\nu =1\] or 2 Hz done
clear
D)
No variation in the deflection will be seen if \[\nu =1\]or 2 Hz done
clear
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question_answer18)
A coil of area \[100c{{m}^{2}}\] has 500 turns. Magnetic field of \[0.1\ weber/metr{{e}^{2}}\] is perpendicular to the coil. The field is reduced to zero in 0.1 second. The induced e.m.f. in the coil is [MP PMT 1991; MH CET (Med.) 1999]
A)
1 V done
clear
B)
5 V done
clear
C)
50 V done
clear
D)
Zero done
clear
View Solution play_arrow
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question_answer19)
A 50 turns circular coil has a radius of \[3\ cm\], it is kept in a magnetic field acting normal to the area of the coil. The magnetic field \[B\] increased from 0.10 tesla to 0.35 tesla in 2 milliseconds. The average induced e.m.f. in the coil is [MP PET 1994]
A)
\[1.77\ volts\] done
clear
B)
\[17.7\ volts\] done
clear
C)
\[177\ volts\] done
clear
D)
\[0.177\ volts\] done
clear
View Solution play_arrow
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question_answer20)
A coil having an area \[2{{m}^{2}}\] is placed in a magnetic field which changes from \[1Wb/{{m}^{2}}\]to \[4Wb/{{m}^{2}}\]in a interval of 2 second. The e.m.f. induced in the coil will be [DPMT 1999; MP PET 2002]
A)
4 V done
clear
B)
3 V done
clear
C)
1.5 V done
clear
D)
2 V done
clear
View Solution play_arrow
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question_answer21)
A coil has 2000 turns and area of\[70c{{m}^{2}}\]. The magnetic field perpendicular to the plane of the coil is \[0.3Wb/{{m}^{2}}\]and takes 0.1sec to rotate through\[{{180}^{o}}\]. The value of the induced e.m.f. will be [MP PET 1993; Similar to AIIMS 1997]
A)
\[8.4V\] done
clear
B)
\[84V\] done
clear
C)
\[42V\] done
clear
D)
\[4.2V\] done
clear
View Solution play_arrow
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question_answer22)
Two different loops are concentric and lie in the same plane. The current in the outer loop is clockwise and increasing with time. The induced current in the inner loop then, is [MP PET 1993]
A)
Clockwise done
clear
B)
Zero done
clear
C)
Counter clockwise done
clear
D)
In a direction that depends on the ratio of the loop radii done
clear
View Solution play_arrow
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question_answer23)
According to Faraday's law of electromagnetic induction [MP PET 1994]
A)
The direction of induced current is such that it opposes the cause producing it done
clear
B)
The magnitude of induced e.m.f. produced in a coil is directly proportional to the rate of change of magnetic flux done
clear
C)
The direction of induced e.m.f. is such that it opposes the cause producing it done
clear
D)
None of the above done
clear
View Solution play_arrow
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question_answer24)
The unit of magnetic flux is [MP PMT 1994; MP PET 1995; AFMC 1998]
A)
\[Weber/{{m}^{2}}\] done
clear
B)
Weber done
clear
C)
Henry done
clear
D)
Ampere/m done
clear
View Solution play_arrow
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question_answer25)
The north pole of a long horizontal bar magnet is being brought closer to a vertical conducting plane along the perpendicular direction. The direction of the induced current in the conducting plane will be [MP PMT 1994]
A)
Horizontal done
clear
B)
Vertical done
clear
C)
Clockwise done
clear
D)
Anticlockwise done
clear
View Solution play_arrow
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question_answer26)
The magnetic field in a coil of 100 turns and 40 square cm area is increased from 1 Tesla to 6 Tesla in 2 second. The magnetic field is perpendicular to the coil. The e.m.f. generated in it is [MP PMT 1994]
A)
\[{{10}^{4}}\,V\] done
clear
B)
1.2 V done
clear
C)
1.0 V done
clear
D)
\[{{10}^{-2}}\,V\] done
clear
View Solution play_arrow
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question_answer27)
The dimensions of magnetic flux are [MP PMT 1994; CBSE PMT 1999]
A)
\[ML{{T}^{-2}}{{A}^{-2}}\] done
clear
B)
\[M{{L}^{2}}{{T}^{-2}}{{A}^{-2}}\] done
clear
C)
\[M{{L}^{2}}{{T}^{-1}}{{A}^{-2}}\] done
clear
D)
\[M{{L}^{2}}{{T}^{-2}}{{A}^{-1}}\] done
clear
View Solution play_arrow
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question_answer28)
Lenz's law gives [MP PMT 1994]
A)
The magnitude of the induced e.m.f. done
clear
B)
The direction of the induced current done
clear
C)
Both the magnitude and direction of the induced current done
clear
D)
The magnitude of the induced current done
clear
View Solution play_arrow
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question_answer29)
The north pole of a bar magnet is moved swiftly downward towards a closed coil and then second time it is raised upwards slowly. The magnitude and direction of the induced currents in the two cases will be of [MP PET 1996] First case Second case
A)
Low value clockwise Higher value anticlockwise done
clear
B)
Low value clockwise Equal value anticlockwise done
clear
C)
Higher value clockwise Low value clockwise done
clear
D)
Higher value anticlockwise Low value clockwise done
clear
View Solution play_arrow
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question_answer30)
A metallic ring connected to a rod oscillates freely like a pendulum. If now a magnetic field is applied in horizontal direction so that the pendulum now swings through the field, the pendulum will
A)
Keep oscillating with the old time period done
clear
B)
Keep oscillating with a smaller time period done
clear
C)
Keep oscillating with a larger time period done
clear
D)
Come to rest very soon done
clear
View Solution play_arrow
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question_answer31)
A circular coil of 500 turns of wire has an enclosed area of \[0.1\,{{m}^{2}}\] per turn. It is kept perpendicular to a magnetic field of induction 0.2 T and rotated by 180° about a diameter perpendicular to the field in 0.1 sec. How much charge will pass when the coil is connected to a galvanometer with a combined resistance of 50 ohms [MP PET 1997]
A)
0.2 C done
clear
B)
0.4 C done
clear
C)
2 C done
clear
D)
4 C done
clear
View Solution play_arrow
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question_answer32)
A coil of 100 turns and area 5 square centimetre is placed in a magnetic field B = 0.2 T. The normal to the plane of the coil makes an angle of 60° with the direction of the magnetic field. The magnetic flux linked with the coil is [MP PMT 1997]
A)
\[5\times {{10}^{-3}}Wb\] done
clear
B)
\[5\times {{10}^{-5}}\,Wb\] done
clear
C)
\[{{10}^{-2}}\,Wb\] done
clear
D)
\[{{10}^{-4}}\,Wb\] done
clear
View Solution play_arrow
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question_answer33)
In a circuit with a coil of resistance 2 ohms, the magnetic flux changes from 2.0 Wb to 10.0 Wb in 0.2 second. The charge that flows in the coil during this time is [MP PMT 1997]
A)
5.0 coulomb done
clear
B)
4.0 coulomb done
clear
C)
1.0 coulomb done
clear
D)
0.8 coulomb done
clear
View Solution play_arrow
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question_answer34)
The direction of induced current is such that it opposes the very cause that has produced it. This is the law of [MP PMT/PET 1998]
A)
Lenz done
clear
B)
Faraday done
clear
C)
Kirchhoff done
clear
D)
Fleming done
clear
View Solution play_arrow
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question_answer35)
To induce an e.m.f. in a coil, the linking magnetic flux [KCET 1994]
A)
Must decrease done
clear
B)
Can either increase or decrease done
clear
C)
Must remain constant done
clear
D)
Must increase done
clear
View Solution play_arrow
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question_answer36)
A solenoid is 1.5 m long and its inner diameter is 4.0 cm. It has three layers of windings of 1000 turns each and carries a current of 2.0 amperes. The magnetic flux for a cross-section of the solenoid is nearly [AMU 1995]
A)
2.5 ´ 10?7 weber done
clear
B)
6.31 ´ 10?6 weber done
clear
C)
5.2 ´ 10?5 weber done
clear
D)
4.1 ´ 10?5 weber done
clear
View Solution play_arrow
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question_answer37)
A coil of 40 W resistance has 100 turns and radius 6 mm is connected to ammeter of resistance of 160 ohms. Coil is placed perpendicular to the magnetic field. When coil is taken out of the field, 32 m C charge flows through it. The intensity of magnetic field will be [RPET 1997]
A)
6.55 T done
clear
B)
5.66 T done
clear
C)
0.655 T done
clear
D)
0.566 T done
clear
View Solution play_arrow
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question_answer38)
Faraday's laws are consequence of conservation of [CBSE PMT 1993; BHU 2002]
A)
Energy done
clear
B)
Energy and magnetic field done
clear
C)
Charge done
clear
D)
Magnetic field done
clear
View Solution play_arrow
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question_answer39)
A magnetic field of 2 ´ 10? 2 T acts at right angles to a coil of area 100 cm2 with 50 turns. The average emf induced in the coil is 0.1 V, when it is removed from the field in time t. The value of t is [CBSE PMT 1992; CPMT 2001]
A)
0.1 sec done
clear
B)
0.01 sec done
clear
C)
1 sec done
clear
D)
20 sec done
clear
View Solution play_arrow
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question_answer40)
The total charge induced in a conducting loop when it is moved in magnetic field depends on [CBSE PMT 1992; ISM Dhanbad 1994]
A)
The rate of change of magnetic flux done
clear
B)
Initial magnetic flux only done
clear
C)
The total change in magnetic flux done
clear
D)
Final magnetic flux only done
clear
View Solution play_arrow
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question_answer41)
A rectangular coil of 20 turns and area of cross- section 25 sq cm has a resistance of 100 ohm. If a magnetic field which is perpendicular to the plane of the coil changes at the rate of 1000 Tesla per second, the current in the coil is [CBSE PMT 1992; Very Similar to MHCET 2002; DPMT 2004]
A)
1.0 ampere done
clear
B)
50 ampere done
clear
C)
0.5 ampere done
clear
D)
5.0 ampere done
clear
View Solution play_arrow
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question_answer42)
The north pole of a magnet is brought near a metallic ring. The direction of the induced current in the ring will be [AIIMS 1999]
A)
Clockwise done
clear
B)
Anticlockwise done
clear
C)
Towards north done
clear
D)
Towards south done
clear
View Solution play_arrow
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question_answer43)
Lenz?s law applies to [DCE 1999]
A)
Electrostatics done
clear
B)
Lenses done
clear
C)
Electro-magnetic induction done
clear
D)
Cinema slides done
clear
View Solution play_arrow
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question_answer44)
If a coil of metal wire is kept stationary in a non-uniform magnetic field, then [BHU 2000]
A)
An e.m.f. is induced in the coil done
clear
B)
A current is induced in the coil done
clear
C)
Neither e.m.f. nor current is induced done
clear
D)
Both e.m.f. and current is induced done
clear
View Solution play_arrow
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question_answer45)
The magnetic flux linked with a coil, in webers, is given by the equations \[\varphi =3{{t}^{2}}+4t+9\]. Then the magnitude of induced e.m.f. at t = 2 second will be [KCET 2000; CPMT 2003; MP PET 2005]
A)
2 volt done
clear
B)
4 volt done
clear
C)
8 volt done
clear
D)
16 volt done
clear
View Solution play_arrow
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question_answer46)
A coil has an area of 0.05 m2 and it has 800 turns. It is placed perpendicularly in a magnetic field of strength \[4\times {{10}^{-5}}\,Wb/{{m}^{2}},\] it is rotated through \[{{90}^{o}}\] in 0.1 sec. The average e.m.f. induced in the coil is [CPMT 2001]
A)
0.056 V done
clear
B)
0.046 V done
clear
C)
0.026 V done
clear
D)
0.016 V done
clear
View Solution play_arrow
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question_answer47)
A moving conductor coil in a magnetic field produces an induced e.m.f. This is in accordance with [AFMC 1993; MH CET 2001, 03]
A)
Amperes law done
clear
B)
Coulomb law done
clear
C)
Lenz?s law done
clear
D)
Faraday?s law done
clear
View Solution play_arrow
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question_answer48)
In the diagram shown if a bar magnet is moved along the common axis of two single turn coils A and B in the direction of arrow [Kerala (Engg.) 2001]
A)
Current is induced only in A & not in B done
clear
B)
Induced currents in A & B are in the same direction done
clear
C)
Current is induced only in B and not in A done
clear
D)
Induced currents in A & B are in opposite directions done
clear
View Solution play_arrow
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question_answer49)
Magnetic flux f (in weber) linked with a closed circuit of resistance 10 ohm varies with time t (in seconds) as \[\varphi =5{{t}^{2}}-4t+1\] The induced electromotive force in the circuit at t = 0.2 sec. is [MP PMT 2001]
A)
0.4 volts done
clear
B)
? 0.4 volts done
clear
C)
? 2.0 volts done
clear
D)
2.0 volts done
clear
View Solution play_arrow
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question_answer50)
The formula for induced e.m.f. in a coil due to change in magnetic flux through the coil is (here A = area of the coil, B = magnetic field) [MP PET 2002]
A)
\[e=-A.\frac{dB}{dt}\] done
clear
B)
\[e=-B.\frac{dA}{dt}\] done
clear
C)
\[e=-\frac{d}{dt}(A.B)\] done
clear
D)
\[e=-\frac{d}{dt}(A\times B)\] done
clear
View Solution play_arrow
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question_answer51)
Lenz?s law is expressed by the following formula (here e = induced e.m.f., f = magnetic flux in one turn and N = number of turns) [MP PET 2002]
A)
\[e=-\varphi \frac{dN}{dt}\] done
clear
B)
\[e=-N\frac{d\varphi }{dt}\] done
clear
C)
\[e=-\frac{d}{dt}\left( \frac{\varphi }{N} \right)\] done
clear
D)
\[e=N\frac{d\varphi }{dt}\] done
clear
View Solution play_arrow
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question_answer52)
A magnet is dropped down an infinitely long vertical copper tube [KCET 2002]
A)
The magnet moves with continuously increasing velocity and ultimately acquires a constant terminal velocity done
clear
B)
The magnet moves with continuously decreasing velocity and ultimately comes to rest done
clear
C)
The magnet moves with continuously increasing velocity but constant acceleration done
clear
D)
The magnet moves with continuously increasing velocity and acceleration done
clear
View Solution play_arrow
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question_answer53)
An aluminium ring B faces an electromagnet A. The current I through A can be altered [Kerala PET 2002]
A)
Whether I increases or decreases, B will not experience any force done
clear
B)
If I decrease, A will repel B done
clear
C)
If I increases, A will attract B done
clear
D)
If I increases, A will repel B done
clear
View Solution play_arrow
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question_answer54)
The magnetic flux linked with a coil at any instant ?t? is given by f = 5t3 ? 100t + 300, the e.m.f. induced in the coil at t = 2 second is [KCET 2003]
A)
? 40 V done
clear
B)
40 V done
clear
C)
140 V done
clear
D)
300 V done
clear
View Solution play_arrow
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question_answer55)
A coil has 1,000 turns and 500 cm2 as its area. The plane of the coil is placed at right angles to a magnetic induction field of \[2\times {{10}^{-5}}\,Wb/{{m}^{2}}\]. The coil is rotated through \[{{180}^{o}}\] in 0.2 seconds. The average e.m.f. induced in the coil, in milli-volts, is [EAMCET 2003]
A)
5 done
clear
B)
10 done
clear
C)
15 done
clear
D)
20 done
clear
View Solution play_arrow
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question_answer56)
When a bar magnet falls through a long hollow metal cylinder fixed with its axis vertical, the final acceleration of the magnet is [BVP 2003]
A)
Equal to zero done
clear
B)
Less than g done
clear
C)
Equal to g done
clear
D)
Equal to g in to beginning and then more than g done
clear
View Solution play_arrow
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question_answer57)
The magnetic flux linked with a vector area \[\overrightarrow{A}\] in a uniform magnetic field \[\overrightarrow{B}\] is [MP PET 2003]
A)
\[\overrightarrow{B}\times \overrightarrow{A}\] done
clear
B)
AB done
clear
C)
\[\overrightarrow{B}\cdot \overrightarrow{A}\] done
clear
D)
\[\frac{B}{A}\] done
clear
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question_answer58)
The magnetic flux linked with a circuit of resistance 100 ohm increases from 10 to 60 webers. The amount of induced charge that flows in the circuit is (in coulomb) [MP PET 2003]
A)
0.5 done
clear
B)
5 done
clear
C)
50 done
clear
D)
100 done
clear
View Solution play_arrow
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question_answer59)
A magnet NS is suspended from a spring and while it oscillates, the magnet moves in and out of the coil C. The coil is connected to a galvanometer G. Then as the magnet oscillates, [KCET 2004]
A)
G shows deflection to the left and right with constant amplitude done
clear
B)
G shows deflection on one side done
clear
C)
G shows no deflection. done
clear
D)
G shows deflection to the left and right but the amplitude steadily decreases. done
clear
View Solution play_arrow
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question_answer60)
A coil having n turns and resistance R W is connected with a galvanometer of resistance \[4R\Omega \]. This combination is moved in time t seconds from a magnetic field W1 weber to W2 weber. The induced current in the circuit is [AIEEE 2004]
A)
\[-\frac{{{W}_{2}}-{{W}_{1}}}{5\ Rnt}\] done
clear
B)
\[-\frac{n({{W}_{2}}-{{W}_{1}})}{5\ Rt}\] done
clear
C)
\[-\frac{({{W}_{2}}-{{W}_{1}})}{Rnt}\] done
clear
D)
\[-\frac{n({{W}_{2}}-{{W}_{1}})}{Rt}\] done
clear
View Solution play_arrow
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question_answer61)
If a copper ring is moved quickly towards south pole of a powerful stationary bar magnet, then [Pb. PMT 2004]
A)
Current flows through the copper ring done
clear
B)
Voltage in the magnet increase done
clear
C)
Current flows in the magnet done
clear
D)
Copper ring will get magnetised done
clear
View Solution play_arrow
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question_answer62)
The magnetic flux linked with coil, in weber is given by the equation, \[\varphi =5{{t}^{2}}+3t+16\]. The induced emf in the coil in the fourth second is [Pb. PMT 2004]
A)
10 V done
clear
B)
30 V done
clear
C)
45 V done
clear
D)
90 V done
clear
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question_answer63)
The coil of area 0.1 m2 has 500 turns. After placing the coil in a magnetic field of strength \[4\times {{10}^{-4}}Wb/{{m}^{2}}\], if rotated through 90o in 0.1 s, the average emf induced in the coil is [Pb. PET 2002]
A)
0.012 V done
clear
B)
0.05 V done
clear
C)
0.1 V done
clear
D)
0.2 V done
clear
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question_answer64)
Magnetic flux in a circuit containing a coil of resistance \[2\Omega \]changes from 2.0 Wb to 10 Wb in 0.2 sec. The charge passed through the coil in this time is [DPMT 2003]
A)
0.8 C done
clear
B)
1.0 C done
clear
C)
5.0 C done
clear
D)
4.0 C done
clear
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question_answer65)
The diagram below shows two coils A and B placed parallel to each other at a very small distance. Coil A is connected to an ac supply. G is a very sensitive galvanometer. When the key is closed [CPMT 1986]
A)
Constant deflection will be observed in the galvanometer for 50 Hz supply done
clear
B)
Visible small variations will be observed in the galvanometer for 50 Hz input done
clear
C)
Oscillations in the galvanometer may be observed when the input ac voltage has a frequency of 1 to 2 Hz done
clear
D)
No variation will be observed in the galvanometer even when the input ac voltage is 1 or 2 Hz done
clear
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question_answer66)
An infinitely long cylinder is kept parallel to an uniform magnetic field B directed along positive z axis. The direction of induced current as seen from the z axis will be [IIT-JEE (Screening) 2005]
A)
Clockwise of the +ve z axis done
clear
B)
Anticlockwise of the +ve z axis done
clear
C)
Zero done
clear
D)
Along the magnetic field done
clear
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question_answer67)
In a magnetic field of 0.05T, area of a coil changes from \[101\,c{{m}^{2}}\] to \[100\,c{{m}^{2}}\] without changing the resistance which is 2W. The amount of charge that flow during this period is [Orissa PMT 2005]
A)
\[2.5\times {{10}^{-6}}\]coulomb done
clear
B)
\[2\times {{10}^{-6}}\]coulomb done
clear
C)
\[{{10}^{-6}}\]coulomb done
clear
D)
\[8\times {{10}^{-6}}\]coulomb done
clear
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question_answer68)
If a coil of 40 turns and area 4.0 cm2 is suddenly removed from a magnetic field, it is observed that a charge of \[2.0\times {{10}^{-4}}C\] flows into the coil. If the resistance of the coil is \[80\Omega \], the magnetic flux density in \[Wb/{{m}^{2}}\] is [MP PET 2005]
A)
0.5 done
clear
B)
1.0 done
clear
C)
1.5 done
clear
D)
2.0 done
clear
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