Solved papers for JEE Main & Advanced Physics Magnetism JEE PYQ-Magnetism

done JEE PYQ-Magnetism Total Questions - 39

• question_answer1) A thin rectangular magnet suspended freely has a period of oscillation equal to T. Now, it is broken into two equal halves (each having half of the original length) and one piece is made to oscillate freely in the same field. If its period of oscillation is T', the ratio T'/T is   [AIEEE 2003]
  A)
  \[\frac{1}{2\sqrt{2}}\]
  done clear
  B)
  \[\frac{1}{2}\]
  done clear
  C)
  2
  done clear
  D)
  \[\frac{1}{4}\]
  done clear
  View Answer play_arrow

• question_answer2) A magnetic needle lying parallel to a magnetic field requires W unit of work to turn it through\[{{60}^{o}}\]. The torque needed to maintain the needle in this position will be                     [AIEEE 2003]
  A)
  \[\sqrt{3}\] W
  done clear
  B)
  W    
  done clear
  C)
  \[(\sqrt{3}/2)\]W
  done clear
  D)
  2 W
  done clear
  View Answer play_arrow

• question_answer3) The magnetic lines of force inside a bar magnet [AIEEE 2003]
  A)
  are from north-pole to south-pole of the magnet
  done clear
  B)
  do not exist
  done clear
  C)
  depend upon the area of cross-section of the bar magnet
  done clear
  D)
  are from south-pole to north-pole of the magnet
  done clear
  View Answer play_arrow

• question_answer4) Curie temperature is the temperature above which                                      [AIEEE 2003]
  A)
  a ferromagnetic material becomes paramagnetic
  done clear
  B)
  a paramagnetic material becomes  diamagnetic
  done clear
  C)
  a ferromagnetic material becomes diamagnetic
  done clear
  D)
  a paramagnetic material becomes ferromagnetic
  done clear
  View Answer play_arrow

• question_answer5) The length of a magnet is large compared to its width and breadth. The time period of its oscillation in a vibration magnetometer is 2 s. The magnet is cut along its length into three equal parts and three parts are then placed on each other with their like poles together. The time period of this combination will be [AIEEE 2004]
  A)
  \[2s\]
  done clear
  B)
  \[2/3\text{ }s\]
  done clear
  C)
  \[2\sqrt{3}\text{ }s\]
  done clear
  D)
  \[2/\sqrt{3}\text{ }s\]
  done clear
  View Answer play_arrow

• question_answer6) A magnetic needle is kept in a non-uniform magnetic field. It experiences      [AIEEE 2005]
  A)
  a torque but not a force   
  done clear
  B)
  neither a force nor a torque
  done clear
  C)
  a force and a torque
  done clear
  D)
  a force but not a torque
  done clear
  View Answer play_arrow

• question_answer7) Needles \[{{N}_{1}},{{N}_{2}}\] and \[{{N}_{3}}\] are made of a ferromagnetic, a paramagnetic and a diamagnetic substance, respectively. A magnet when brought close to them will    [AIEEE 2006]
  A)
  Attract\[{{N}_{1}}\]and\[{{N}_{2}}\]strongly but repel\[{{N}_{3}}\]
  done clear
  B)
  Attract\[{{N}_{1}}\]strongly, \[{{N}_{2}}\]weakly and repel\[{{N}_{3}}\] weakly
  done clear
  C)
  Attract\[{{N}_{1}}\]strongly, but repel\[{{N}_{2}}\]and\[{{N}_{3}}\]weakly
  done clear
  D)
  attract all three of them
  done clear
  View Answer play_arrow

• question_answer8) Relative permittivity and permeability of a material are \[{{\varepsilon }_{r}}\] and \[{{\mu }_{r}}\], respectively. Which of the following values of these quantifies are allowed for a diamagnetic material? [AIEEE 2008]
  A)
              \[{{\varepsilon }_{r}}=0.5,\,{{\mu }_{r}}=0.5\]
  done clear
  B)
              \[{{\varepsilon }_{r}}=1.5,\,{{\mu }_{r}}=1.5\]
  done clear
  C)
              \[{{\varepsilon }_{r}}=0.5,\,{{\mu }_{r}}=1.5\]
  done clear
  D)
              \[{{\varepsilon }_{r}}=1.5,\,{{\mu }_{r}}=0.5\]
  done clear
  View Answer play_arrow

• question_answer9) A bar magnet of length 6 cm has a magnetic moment of \[4J\,{{T}^{-1}}.\]Find the strength of magnetic field at a distance of 200 cm from the centre of the magnet along its equatorial line. [JEE ONLINE 07-05-2012]
  A)
  \[4\times {{10}^{-8}}\text{tesla}\]
  done clear
  B)
  \[3.5\times {{10}^{-8}}\text{tesla}\]
  done clear
  C)
  \[5\times {{10}^{-8}}\text{tesla}\]
  done clear
  D)
  \[3\times {{10}^{-8}}\text{tesla}\]
  done clear
  View Answer play_arrow

• question_answer10) Two short bar magnets of length 1 cm each have magnetic moments 1.20\[A{{m}^{2}}\]and 1.00\[A{{m}^{2}}\]respectively. They are placed on a horizontal table parallel to each other with their N poles pointing towards the South. They have a common magnetic equator and are separated by a distance of 20.0 cm. The value of the resultant horizontal magnetic induction at the mid - point O of the line joining their centre is close to (Horizontal component of earth′s magnetic induction is\[3.6\times {{10}^{-5}}Wb/{{m}^{2}}\])  [JEE MAIN 2013]
  A)
  \[3.6\times {{10}^{-5}}Wb/{{m}^{2}}\]         
  done clear
  B)
  \[2.56\times {{10}^{-4}}Wb/{{m}^{2}}\]
  done clear
  C)
  \[3.50\times {{10}^{-4}}Wb/{{m}^{2}}\]
  done clear
  D)
  \[5.80\times {{10}^{-4}}Wb/{{m}^{2}}\]
  done clear
  View Answer play_arrow

• question_answer11) The earth’s magnetic field lines resemble of a dipole at the centre of the earth. It the magnetic moment of this dipole is close to \[8\times {{10}^{22}}\]\[\text{A}{{\text{m}}^{\text{2}}}\], the value of earth’s magnetic field near the equator is close to (radius of earth = \[\text{6}\text{.4}\times \text{1}{{\text{0}}^{\text{6}}}\operatorname{m}\])        [JEE ONLINE 25-04-2013]
  A)
              0.6 Gauss
  done clear
  B)
              1.2 Gauss
  done clear
  C)
              1.8 Gauss
  done clear
  D)
              032 Gauss
  done clear
  View Answer play_arrow

• question_answer12) The coercivity of a small magnet where the Ferro magnet gets demagnetized is \[3\times {{10}^{3}}A\,{{m}^{-1}}.\]The current required to be passed in a solenoid of length 10 cm and number of turns 100, so that the magnet gets demagnetized when inside the solenoid, is:                       [JEE MAIN 2014]
  A)
  3 A
  done clear
  B)
  6 A
  done clear
  C)
  30 mA
  done clear
  D)
  60 mA
  done clear
  View Answer play_arrow

• question_answer13) 

  The mid points of two small magnetic dipoles of length d in end-on positions, are separated by a distance x, (x >> d).

  The force between them is proportional to \[{{x}^{-n}}\] where n is:           [JEE ONLINE 09-04-2014]

  A)
  1
  done clear
  B)
  2
  done clear
  C)
  3
  done clear
  D)
  4
  done clear
  View Answer play_arrow

• question_answer14) The magnetic field of earth at the equator is approximately \[4\times {{10}^{-5}}T.\]The radius of earth is \[6.4\times {{10}^{6}}m.\] Then the dipolemoment of the earth will be nearly of the order of:                           [JEE ONLINE 09-04-2014]
  A)
  \[{{10}^{23}}A{{m}^{2}}\]
  done clear
  B)
  \[{{10}^{20}}A{{m}^{2}}\]
  done clear
  C)
  \[{{10}^{16}}A{{m}^{2}}\]
  done clear
  D)
  \[{{10}^{10}}A{{m}^{2}}\]
  done clear
  View Answer play_arrow

• question_answer15) 

  Three identical bars A, B and C are made of different magnetic materials. When kept in a uniform magnetic field, the field lines around them look as follows:             [JEE ONLINE 11-04-2014]

  A)
  \[A\leftrightarrow D,B\leftrightarrow P,C\leftrightarrow F\]
  done clear
  B)
  \[A\leftrightarrow F,B\leftrightarrow D,C\leftrightarrow P\]
  done clear
  C)
  \[A\leftrightarrow P,B\leftrightarrow F,C\leftrightarrow D\]
  done clear
  D)
  \[A\leftrightarrow F,B\leftrightarrow P,C\leftrightarrow D\]
  done clear
  View Answer play_arrow

• question_answer16) An example of a perfect diamagnet is a superconductor. This implies that when a superconductor is put in a magnetic field of intensity B, the magnetic field \[{{B}_{s}}\] inside the  superconductor will be such that: [JEE ONLINE 19-04-2014]
  A)
  \[{{B}_{s}}=-B\]
  done clear
  B)
  \[{{B}_{s}}=0\]
  done clear
  C)
  \[{{B}_{s}}=B\]
  done clear
  D)
  \[{{B}_{s}}<B\]but\[Bs\ne 0\]
  done clear
  View Answer play_arrow

• question_answer17) A 25 cm long solenoid has radius 2 cm and 500 total number of turns. It carries a current of 15 A. If it is equivalent to a magnet of the same size and magnetization \[\overset{\to }{\mathop{M}}\,\](magnetic moment/volume), then \[|\overset{\to }{\mathop{M}}\,|\]is:          [JEE ONLINE 10-04-2015]
  A)
  \[30000\,A{{m}^{-1}}\]
  done clear
  B)
  \[3\pi \,A{{m}^{-1}}\]
  done clear
  C)
              \[30000\pi \,A{{m}^{-1}}\]
  done clear
  D)
  \[300\,A{{m}^{-1}}\]
  done clear
  View Answer play_arrow

• question_answer18) 

  A short bar magnet is placed in the magnetic meridian of the earth with North Pole pointing north. Neutral points are found at a distance of 30 cm from the magnet on the East - West line, drawn through the middle point of the magnet.

  The magnetic moment of the magnet in \[A{{m}^{2}}\]is close to: [JEE MAIN 11-04-2015]

  (Given \[\frac{{{\mu }_{0}}}{4\pi }={{10}^{-7}}\] in SI units and \[{{B}_{H}}=\]Horizontal component of earth's magnetic field \[=3.6\times {{10}^{-}}^{5}\] Tesla.)

  A)
             9.7
  done clear
  B)
  4.9
  done clear
  C)
  19.4
  done clear
  D)
  14.6
  done clear
  View Answer play_arrow

• question_answer19) 

  Hysteresis loops for two magnetic materials A and B are given below: [JEE MAIN - I 3-4-2016]

  These materials are used to make magnets for electric generators, transformer core and electromagnet core. Then it is proper to use;

  A)
  B for electromagnets and transformers.
  done clear
  B)
  A for electric generators and transformers.
  done clear
  C)
  A for electromagnets and B for electric transformers.
  done clear
  D)
  A for transformers and B for electric generators.
  done clear
  View Answer play_arrow

• question_answer20) A magnetic dipole is acted upon by two magnetic fields which are inclined to each other a tan angle of 75°. One of the fields has magnitude of 15mT. The dipole attains stable equilibrium at an angle 30° with this field. The magnitude of the other field (in mT) is close to:                              [JEE ONLINE 09-04-2016]
  A)
  11
  done clear
  B)
  1060
  done clear
  C)
  36
  done clear
  D)
  1
  done clear
  View Answer play_arrow

• question_answer21) A fighter plane of length 20m, wing span (distance from tip of one wing to the tip of the other wing) of 15 m and height 5m is flying towards east over Delhi. Its speed is \[240\,m{{s}^{-1}}\]The earth's magnetic field over Delhi is \[5\times {{10}^{-5}}\]T with the declination angle \[\sim {{0}^{o}}\] and dip of \[\theta \] such that sin \[\theta =\frac{2}{3}\].If the voltage developed is \[{{V}_{B}}\] between the lower and upper side of the plane and \[{{V}_{w}}\]. between the tips the wings then \[{{V}_{B}}\] and VW are closed to:                           [JEE ONLINE 10-04-2016]
  A)
              \[{{V}_{B}}=40mV,{{V}_{w}}=135mV\]with left side of pilot at higher voltage.
  done clear
  B)
              \[{{V}_{B}}=40mV,{{V}_{w}}=135mV\]with right side of pilot at high voltage.
  done clear
  C)
              \[{{V}_{B}}=45mV,{{V}_{w}}=120mV\]with left side of pilot at higher voltage.
  done clear
  D)
              \[{{V}_{B}}=45mV,{{V}_{w}}=120mV\]with right side of pilot at higher voltage.
  done clear
  View Answer play_arrow

• question_answer22) A magnetic needle of magnetic moment \[6.7\times {{10}^{-2}}\,A{{m}^{2}}\]and moment of inertia \[7.5\times {{10}^{-6}}\,kg\,{{m}^{2}}\]is performing simple harmonic oscillations in a magnetic field of 0.01 T. Time taken for 10 complete oscillations is: [JEE Main 2017]
  A)
  6.98 s
  done clear
  B)
  8.76 s
  done clear
  C)
  6.65 s
  done clear
  D)
  8.89 s
  done clear
  View Answer play_arrow

• question_answer23) A magentic dipole in a constant magnetic field has -                                  [JEE Online 08-04-2017]
  A)
  maximum potential energy when the torque is maximum
  done clear
  B)
  zero potential energy when the torque is maximum
  done clear
  C)
  zero potential energy when the torque is minimum
  done clear
  D)
  minimum potential energy when the torque is maximum
  done clear
  View Answer play_arrow

• question_answer24) 

  The B-H curve for a Ferro magnet is shown in the figure. The Ferro magnet is placed inside a ling solenoid with 1000 turns/cm. The current that should be passed in the solenoid to demagnetise the Ferro magnet completely is:

  [JEE Online 15-04-2018]

  A)
  \[2mA\]
  done clear
  B)
  \[1mA\]
  done clear
  C)
  \[40\mu A\]
  done clear
  D)
  \[20\mu A\]
  done clear
  View Answer play_arrow

• question_answer25) A bar magnet is demagnetized by inserting it inside a solenoid of length 0.2 m, 100 turns, and carrying a current of 5.2 A. The coercivity of the bar magnet is:                                                     [JEE Main 09-Jan-2019 Morning]
  A)
  2600 A/m
  done clear
  B)
  1200 A/m
  done clear
  C)
              520 A/m
  done clear
  D)
  285 A/m
  done clear
  View Answer play_arrow

• question_answer26) 

  In the given circuit the internal resistance of the 18 V cell is negligible. If \[{{R}_{1}}\,\,=\,\,400\,\Omega \],  \[{{R}_{3}}=100\text{ }\Omega \] and \[{{R}_{4}}=500\Omega \]and the reading of an ideal voltmeter across \[{{R}_{4}}\] is 5 V, then the value of \[{{R}_{2}}\] will be: [JEE Main 09-Jan-2019 Evening]

  A)
  \[550\,\,\Omega \]
  done clear
  B)
  \[450\,\,\Omega \]
  done clear
  C)
  \[230\,\,\Omega \]
  done clear
  D)
  \[300\,\,\Omega \]
  done clear
  View Answer play_arrow

• question_answer27) A magnet of total magnetic moment \[{{10}^{-}}^{2}\widehat{i}\,A-{{m}^{2}}\] is placed in a time varying magnetic field, \[B\widehat{i}\left( cos\text{ }\omega t \right)\] where \[B=1\] Tesla and\[\omega =0.125\text{ }rad/s\]. The work done for reversing the direction of the magnetic moment at \[t=1\] second, is- [JEE Main 10-Jan-2019 Morning]
  A)
  0.014 J
  done clear
  B)
  0.028 J
  done clear
  C)
  0.01 J
  done clear
  D)
  0.007 J
  done clear
  View Answer play_arrow

• question_answer28) A solid metal cube of edge length 2 cm is moving in a positive y-direction at a constant speed of 6 m/s. There it’, a uniform magnetic field of 0.1 T in the positive z- direction. The potential difference between the two faces of the cube perpendicular to the x-axis, is - [JEE Main 10-Jan-2019 Morning]
  A)
  2 mV
  done clear
  B)
  12 mV
  done clear
  C)
  6 mV
  done clear
  D)
  1 mV
  done clear
  View Answer play_arrow

• question_answer29) At some location on earth the horizontal component of earth’s magnetic field\[18\times {{10}^{-}}^{6}T\]. At this location, magnetic needle of length 0.12 m and pole strength 1.8 Am is suspended from its mid-point using a thread, it makes \[45{}^\circ \] angle with horizontal in equilibrium. To keep this needle horizontal, the vertical force that should be applied at one of its ends is-         [JEE Main 10-Jan-2019 Evening]
  A)
  \[3.6\times {{10}^{-5}}\,N\]
  done clear
  B)
  \[1.8\times {{10}^{-5}}\text{ }N\]
  done clear
  C)
  \[1.3\times {{10}^{-5}}\,N\]
  done clear
  D)
  \[6.5\times {{10}^{-5}}\,N\]
  done clear
  View Answer play_arrow

• question_answer30) A hope and a solid cylinder of same mass and radius are made of a permanent magnetic material with their magnetic moment parallel to their respective axes. But the magnetic moment of hoop is twice of solid cylinder. They are placed in a uniform magnetic field in such a manner angle with the field. If the oscillation periods of hoop and cylinder are \[{{T}_{h}}\text{ }and\text{ }{{T}_{c}}\] respectively, then- [JEE Main 10-Jan-2019 Evening]
  A)
  \[{{T}_{h}}=1.5\text{ }{{T}_{c}}\]
  done clear
  B)
  \[{{T}_{h}}={{T}_{c}}\]
  done clear
  C)
  \[{{T}_{h}}=2{{T}_{c}}\]
  done clear
  D)
  \[{{T}_{h}}=0.5{{T}_{c}}\]
  done clear
  View Answer play_arrow

• question_answer31) In an experiment, electrons are accelerated, from rest, by applying a voltage of 500 V. Calculate the radius of the path if a magnetic field 100 mT is then applied. [Charge of the electron \[=1.6\times {{10}^{-16}}C,\] Mass of the electron \[=9.1\times {{10}^{-31}}kg\]]                                                        [JEE Main 11-Jan-2019 Morning]
  A)
  \[7.5m\]
  done clear
  B)
  \[7.5\times {{10}^{-2}}m\]
  done clear
  C)
  \[7.5\times {{10}^{-4}}m\]
  done clear
  D)
  \[7.5\times {{10}^{-3}}m\]
  done clear
  View Answer play_arrow

• question_answer32) A paramagnetic substance in the form of a cube with sides 1 cm has a magnetic dipole moment of \[20\times {{10}^{-6}}J/T\] when a magnetic intensity of \[60\times {{10}^{3}}A/m\]is applied. Its magnetic susceptibility is- [JEE Main 11-Jan-2019 Evening]
  A)
  \[3.3\times {{10}^{-2}}\]
  done clear
  B)
  \[4.3\times {{10}^{-2}}\]
  done clear
  C)
  \[3.3\times {{10}^{-4}}\]
  done clear
  D)
  \[2.3\times {{10}^{-2}}\]
  done clear
  View Answer play_arrow

• question_answer33) 

  As shown in, the figure, two infinitely long, identical wires are bent by \[90{}^\circ \] and placed in such a way that the segments LP and QM are along the x-axis, while segments PS and QN are parallel to the y-axis. If OP=OQ=4cm, and the magnitude of the magnetic field at C) is\[{{10}^{-4}}T,\] and the two wires carry equal currents (see figure), the magnitude of the current in each wire and the direction of the magnetic field at O will be- [JEE Main 12-Jan-2019 Morning]

  \[({{\mu }_{0}}=4\pi \times {{10}^{-7}}N{{A}^{-2}})\]

  A)
  20 A, perpendicular into the page 
  done clear
  B)
  40 A, perpendicular into the page 
  done clear
  C)
  20 A, perpendicular out of the page          
  done clear
  D)
  40 A, perpendicular out of the page.         
  done clear
  View Answer play_arrow

• question_answer34) A paramagnetic material has\[{{10}^{28}}\,\,atoms/{{m}^{3}}\]. Its magnetic susceptibility at temperature 350 K is \[2.8\times {{10}^{-4}}.\] Its susceptibility at 300 K is-                  [JEE Main 12-Jan-2019 Evening]
  A)
  \[3.267\times {{10}^{-4}}\]
  done clear
  B)
  \[3.672\times {{10}^{-4}}\]
  done clear
  C)
  \[2.672\times {{10}^{-4}}\]
  done clear
  D)
  \[3.726\times {{10}^{-4}}\]
  done clear
  View Answer play_arrow

• question_answer35) 

  Two magnetic dipoles X and Y are placed at a separation d, with their axes perpendicular to each other. The dipole moment of Y is twice that of X. A particle of charge q is passing, through their midpoint P, at angle \[\theta ={{45}^{o}}\]with the horizontal line, as shown in figure. What would be the magnitude of force on the particle at that instant? (d is much larger than the dimensions of the dipole)  [JEE Main 8-4-2019 Afternoon]

  A)
  \[\sqrt{2}\left( \frac{{{\mu }_{0}}}{4\pi } \right)\frac{M}{{{(d/2)}^{3}}}\times q\text{v}\]           
  done clear
  B)
  \[\left( \frac{{{\mu }_{0}}}{4\pi } \right)\frac{2M}{{{(d/2)}^{3}}}\times q\text{v}\]
  done clear
  C)
  \[\left( \frac{{{\mu }_{0}}}{4\pi } \right)\frac{M}{{{(d/2)}^{3}}}\times q\text{v}\]
  done clear
  D)
  0
  done clear
  View Answer play_arrow

• question_answer36) A moving coil galvanometer has a coil with 175 turns and area \[1c{{m}^{2}}.\]It uses a torsion band of torsion constant \[{{10}^{-6}}\] N-m/rad. The coil is placed in a maganetic field B parallel to its plane. The coil deflects by\[1{}^\circ \]for a current of 1 mA. The value of B (in Tesla) is approximately: [JEE Main 9-4-2019 Afternoon]
  A)
  \[{{10}^{-3}}\]
  done clear
  B)
  \[{{10}^{-1}}\]
  done clear
  C)
  \[{{10}^{-4}}\]
  done clear
  D)
  \[{{10}^{-2}}\]
  done clear
  View Answer play_arrow

• question_answer37) 

  In a meter bridge experiment, the circuit diagram and the corresponding observation table are shown in figure

  SI. No. \[R(\Omega )\] \[l(cm)\] 1. 1000 60 2. 100 13 3. 10 1.5 4. 1 1.0 Which of the readings is inconsistent? [JEE Main 10-4-2019 Morning]

  A)
  4
  done clear
  B)
  1
  done clear
  C)
  2
  done clear
  D)
  3
  done clear
  View Answer play_arrow

• question_answer38) A magnetic compass needle oscillates 30 times per minute at a place where the dip is \[45{}^\text{o},\]and 40 times per minute where the dip is \[30{}^\text{o}\]. If \[{{B}_{1}}\]and \[{{B}_{2}}\]are respectively the total magnetic field due to the earth at the two places, then the ratio \[{{B}_{1}}/{{B}_{2}}\]is best given by: [JEE Main Held on 12-4-2019 Morning]
  A)
  2.2
  done clear
  B)
  1.8       
  done clear
  C)
  0.7
  done clear
  D)
  3.6
  done clear
  View Answer play_arrow

• question_answer39) 

  The figure gives experimentally measured B vs. H variation in a ferromagnetic material. The retentivity, co-ercivity and saturation, respectively, of the material are [JEE MAIN Held on 07-01-2020 Evening]

  A)
  1.0 T, 50 A/m and 1.5 T
  done clear
  B)
  1.5 T, 50 A/m and 1.0 T
  done clear
  C)
  1.5 T, 50 A/m and 1.0 T
  done clear
  D)
  150 A/m, 1.0 T and 1.5 T
  done clear
  View Answer play_arrow