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MCQOPTIONS
This section includes 12583 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 7001. |
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. | \[e=-\varphi \frac{dN}{dt}\] |
| B. | \[e=-N\frac{d\varphi }{dt}\] |
| C. | \[e=-\frac{d}{dt}\left( \frac{\varphi }{N} \right)\] |
| D. | \[e=N\frac{d\varphi }{dt}\] |
| Answer» C. \[e=-\frac{d}{dt}\left( \frac{\varphi }{N} \right)\] | |
| 7002. |
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. | \[e=-A.\frac{dB}{dt}\] |
| B. | \[e=-B.\frac{dA}{dt}\] |
| C. | \[e=-\frac{d}{dt}(A.B)\] |
| D. | \[e=-\frac{d}{dt}(A\times B)\] |
| Answer» D. \[e=-\frac{d}{dt}(A\times B)\] | |
| 7003. |
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 |
| B. | No current will be induced in a coil |
| C. | Only an e.m.f. will be induced in the coil |
| D. | An e.m.f. and a current both will be induced in the coil |
| Answer» C. Only an e.m.f. will be induced in the coil | |
| 7004. |
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 |
| B. | ? 0.4 volts |
| C. | ? 2.0 volts |
| D. | 2.0 volts |
| Answer» E. | |
| 7005. |
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 |
| B. | Induced currents in A & B are in the same direction |
| C. | Current is induced only in B and not in A |
| D. | Induced currents in A & B are in opposite directions |
| Answer» E. | |
| 7006. |
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 |
| B. | 0.046 V |
| C. | 0.026 V |
| D. | 0.016 V |
| Answer» E. | |
| 7007. |
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 |
| B. | Coulomb law |
| C. | Lenz?s law |
| D. | Faraday?s law |
| Answer» E. | |
| 7008. |
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 |
| B. | 4 volt |
| C. | 8 volt |
| D. | 16 volt |
| Answer» E. | |
| 7009. |
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 |
| B. | A current is induced in the coil |
| C. | Neither e.m.f. nor current is induced |
| D. | Both e.m.f. and current is induced |
| Answer» D. Both e.m.f. and current is induced | |
| 7010. |
Lenz?s law applies to [DCE 1999] |
| A. | Electrostatics |
| B. | Lenses |
| C. | Electro-magnetic induction |
| D. | Cinema slides |
| Answer» D. Cinema slides | |
| 7011. |
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 |
| B. | 50 ampere |
| C. | 0.5 ampere |
| D. | 5.0 ampere |
| Answer» D. 5.0 ampere | |
| 7012. |
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 |
| B. | Anticlockwise |
| C. | Towards north |
| D. | Towards south |
| Answer» C. Towards north | |
| 7013. |
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 |
| B. | Initial magnetic flux only |
| C. | The total change in magnetic flux |
| D. | Final magnetic flux only |
| Answer» D. Final magnetic flux only | |
| 7014. |
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. | \[Q=\frac{\Delta \varphi }{\Delta t}\] |
| B. | \[Q=\frac{\Delta \varphi }{\Delta t}\times R\] |
| C. | \[Q=-\frac{\Delta \varphi }{\Delta t}+R\] |
| D. | \[Q=\frac{\Delta \varphi }{R}\] |
| Answer» E. | |
| 7015. |
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 |
| B. | 0.01 sec |
| C. | 1 sec |
| D. | 20 sec |
| Answer» B. 0.01 sec | |
| 7016. |
Faraday's laws are consequence of conservation of [CBSE PMT 1993; BHU 2002] |
| A. | Energy |
| B. | Energy and magnetic field |
| C. | Charge |
| D. | Magnetic field |
| Answer» B. Energy and magnetic field | |
| 7017. |
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 |
| B. | 5.66 T |
| C. | 0.655 T |
| D. | 0.566 T |
| Answer» E. | |
| 7018. |
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 |
| B. | 6.31 ´ 10?6 weber |
| C. | 5.2 ´ 10?5 weber |
| D. | 4.1 ´ 10?5 weber |
| Answer» C. 5.2 ´ 10?5 weber | |
| 7019. |
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 |
| B. | Faraday |
| C. | Kirchhoff |
| D. | Fleming |
| Answer» B. Faraday | |
| 7020. |
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 |
| B. | 4.0 coulomb |
| C. | 1.0 coulomb |
| D. | 0.8 coulomb |
| Answer» C. 1.0 coulomb | |
| 7021. |
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 |
| B. | 0.4 C |
| C. | 2 C |
| D. | 4 C |
| Answer» C. 2 C | |
| 7022. |
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. | \[5\times {{10}^{-3}}Wb\] |
| B. | \[5\times {{10}^{-5}}\,Wb\] |
| C. | \[{{10}^{-2}}\,Wb\] |
| D. | \[{{10}^{-4}}\,Wb\] |
| Answer» B. \[5\times {{10}^{-5}}\,Wb\] | |
| 7023. |
In electromagnetic induction, the induced charge in a coil is independent of |
| A. | Change in the flux |
| B. | Time |
| C. | Resistance in the circuit |
| D. | None of the above |
| Answer» C. Resistance in the circuit | |
| 7024. |
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 |
| B. | Low value clockwise Equal value anticlockwise |
| C. | Higher value clockwise Low value clockwise |
| D. | Higher value anticlockwise Low value clockwise |
| Answer» E. | |
| 7025. |
Lenz's law gives [MP PMT 1994] |
| A. | The magnitude of the induced e.m.f. |
| B. | The direction of the induced current |
| C. | Both the magnitude and direction of the induced current |
| D. | The magnitude of the induced current |
| Answer» C. Both the magnitude and direction of the induced current | |
| 7026. |
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. | \[{{10}^{4}}\,V\] |
| B. | 1.2 V |
| C. | 1.0 V |
| D. | \[{{10}^{-2}}\,V\] |
| Answer» D. \[{{10}^{-2}}\,V\] | |
| 7027. |
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 |
| B. | Vertical |
| C. | Clockwise |
| D. | Anticlockwise |
| Answer» E. | |
| 7028. |
The unit of magnetic flux is [MP PMT 1994; MP PET 1995; AFMC 1998] |
| A. | \[Weber/{{m}^{2}}\] |
| B. | Weber |
| C. | Henry |
| D. | Ampere/m |
| Answer» C. Henry | |
| 7029. |
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 |
| B. | The magnitude of induced e.m.f. produced in a coil is directly proportional to the rate of change of magnetic flux |
| C. | The direction of induced e.m.f. is such that it opposes the cause producing it |
| D. | None of the above |
| Answer» C. The direction of induced e.m.f. is such that it opposes the cause producing it | |
| 7030. |
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. | \[8.4V\] |
| B. | \[84V\] |
| C. | \[42V\] |
| D. | \[4.2V\] |
| Answer» C. \[42V\] | |
| 7031. |
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 |
| B. | 3 V |
| C. | 1.5 V |
| D. | 2 V |
| Answer» C. 1.5 V | |
| 7032. |
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 |
| B. | 5 V |
| C. | 50 V |
| D. | Zero |
| Answer» C. 50 V | |
| 7033. |
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 |
| B. | Visible small oscillations will be observed in the galvanometer if \[\nu \]is about 50 Hz |
| C. | Oscillations in the deflection will be observed clearly if \[\nu =1\] or 2 Hz |
| D. | No variation in the deflection will be seen if \[\nu =1\]or 2 Hz |
| Answer» D. No variation in the deflection will be seen if \[\nu =1\]or 2 Hz | |
| 7034. |
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 |
| B. | 0.5 |
| C. | 1 |
| D. | 5 |
| Answer» E. | |
| 7035. |
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 |
| B. | \[I\] increases |
| C. | \[Q\] remains same |
| D. | \[Q\] increases |
| Answer» E. | |
| 7036. |
The direction of induced e.m.f. during electromagnetic induction is given by [MP PET 1994, 96] |
| A. | Faraday's law |
| B. | Lenz's law |
| C. | Maxwell's law |
| D. | Ampere's law |
| Answer» C. Maxwell's law | |
| 7037. |
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 |
| B. | 0.5 amp |
| C. | 0.05 amp |
| D. | \[5\times {{10}^{8}}\ amp\] |
| Answer» B. 0.5 amp | |
| 7038. |
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 |
| B. | More in first case/Equal in both case |
| C. | Less in first case/More in second case |
| D. | Less in first case/Equal in both case |
| Answer» C. Less in first case/More in second case | |
| 7039. |
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 |
| B. | \[{{10}^{-5}}\]weber |
| C. | \[{{10}^{5}}\]weber |
| D. | 100 weber |
| Answer» B. \[{{10}^{-5}}\]weber | |
| 7040. |
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 |
| B. | Less than that due to gravity |
| C. | More than that due to gravity |
| D. | Depends on the diameter of the ring and the length of the magnet |
| Answer» C. More than that due to gravity | |
| 7041. |
In electromagnetic induction, the induced e.m.f. in a coil is independent of [CPMT 1984] |
| A. | Change in the flux |
| B. | Time |
| C. | Resistance of the circuit |
| D. | None of the above |
| Answer» D. None of the above | |
| 7042. |
Two forces are such that the sum of their magnitudes is 18 N and their resultant is perpendicular to the smaller force and magnitude of resultant is 12 N. Then the magnitudes of the forces are [AIEEE 2002] |
| A. | 12 N, 6 N |
| B. | 13 N, 5N |
| C. | 10 N, 8 N |
| D. | 16 N, 2 N |
| Answer» C. 10 N, 8 N | |
| 7043. |
The resultant of two forces, one double the other in magnitude, is perpendicular to the smaller of the two forces. The angle between the two forces is [KCET 2002] |
| A. | \[{{60}^{\text{o}}}\] |
| B. | \[{{120}^{\text{o}}}\] |
| C. | \[{{150}^{\text{o}}}\] |
| D. | \[{{90}^{\text{o}}}\] |
| Answer» C. \[{{150}^{\text{o}}}\] | |
| 7044. |
The resultant of two forces \[3P\] and \[2P\]is R. If the first force is doubled then the resultant is also doubled. The angle between the two forces is [KCET 2001] |
| A. | \[{{60}^{\text{o}}}\] |
| B. | \[{{120}^{o}}\] |
| C. | \[{{70}^{o}}\] |
| D. | \[{{180}^{o}}\] |
| Answer» C. \[{{70}^{o}}\] | |
| 7045. |
The resultant force of 5 N and 10 N cannot be [RPET 2000] |
| A. | 12 N |
| B. | 8 N |
| C. | 4 N |
| D. | 5 N |
| Answer» D. 5 N | |
| 7046. |
An object is subjected to a force in the north-east direction. To balance this force, a second force should be applied in the direction [KCET 1994] |
| A. | North-East |
| B. | South |
| C. | South-West |
| D. | West |
| Answer» D. West | |
| 7047. |
Two forces with equal magnitudes F act on a body and the magnitude of the resultant force is F/3. The angle between the two forces is [MP PMT 1999] |
| A. | \[{{\cos }^{-1}}\left( -\frac{17}{18} \right)\] |
| B. | \[{{\cos }^{-1}}\left( -\frac{1}{3} \right)\] |
| C. | \[{{\cos }^{-1}}\left( \frac{2}{3} \right)\] |
| D. | \[{{\cos }^{-1}}\left( \frac{8}{9} \right)\] |
| Answer» B. \[{{\cos }^{-1}}\left( -\frac{1}{3} \right)\] | |
| 7048. |
When a body is stationary [NCERT 1978] |
| A. | There is no force acting on it |
| B. | The force acting on it is not in contact with it |
| C. | The combination of forces acting on it balances each other |
| D. | The body is in vacuum |
| Answer» D. The body is in vacuum | |
| 7049. |
Two forces of magnitude F have a resultant of the same magnitude F. The angle between the two forces is [CBSE PMT 1990] |
| A. | \[45{}^\circ \] |
| B. | \[120{}^\circ \] |
| C. | \[150{}^\circ \] |
| D. | \[{{60}^{\text{o}}}\] |
| Answer» C. \[150{}^\circ \] | |
| 7050. |
A block is kept on a frictionless inclined surface with angle of inclination 'a'. The incline is given an acceleration 'a' to keep the block stationary. Then a is equal to [AIEEE 2005] |
| A. | \[g\] |
| B. | \[g\,tan\alpha \] |
| C. | \[g/\,tan\alpha \] |
| D. | \[g\,cosec\alpha \] |
| Answer» C. \[g/\,tan\alpha \] | |