Magnetic Effects of Current & Magnetism · JEE Main previous year questions

2023 37 questions

1. Q602023 · 12 Apr 2023 · Shift 1· Numerical answer

   A compass needle oscillates 20 times per minute at a place where the dip is $30^{\circ }$ and 30 times per minute where the dip is $60^{\circ }$. The ratio of total magnetic field due to the earth at two places respectively is $\frac{4}{\sqrt{x}}$. The value of $x$ is _________.

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   Answer: 243

2. Q442023 · 11 Apr 2023 · Shift 1

   The free space inside a current carrying toroid is filled with a material of susceptibility $2\times 10^{-2}$. The percentage increase in the value of magnetic field inside the toroid will be

   1. A.0.1%
   2. B.1%
   3. C.2%
   4. D.0.2%
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   Answer: C

3. Q542023 · 11 Apr 2023 · Shift 1· Numerical answer
   
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   Answer: 8

4. Q332023 · 11 Apr 2023 · Shift 2

   An electron is allowed to move with constant velocity along the axis of current carrying straight solenoid. A. The electron will experience magnetic force along the axis of the solenoid. B. The electron will not experience magnetic force. C. The electron will continue to move along the axis of the solenoid. D. The electron will be accelerated along the axis of the solenoid. E. The electron will follow parabolic path-inside the solenoid. Choose the correct answer from the options given below:

   1. A.B, C and D only
   2. B.B and C only
   3. C.A and D only
   4. D.B and E only
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   Answer: B

5. Q352023 · 11 Apr 2023 · Shift 2

   Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: A bar magnet dropped through a metallic cylindrical pipe takes more time to come down compared to a non-magnetic bar with same geometry and mass. Reason R: For the magnetic bar, Eddy currents are produced in the metallic pipe which oppose the motion of the magnetic bar. In the light of the above statements, choose the correct answer from the options given below

   1. A.A is true but R is false
   2. B.A is false but R is true
   3. C.Both A and R are true but R is NOT the correct explanation of A
   4. D.Both A and R are true and R is the correct explanation of A
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   Answer: D

6. Q552023 · 11 Apr 2023 · Shift 2· Numerical answer
   
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   Answer: 150

7. Q582023 · 10 Apr 2023 · Shift 1· Numerical answer

   The current required to be passed through a solenoid of 15 cm length and 60 turns in order of demagnetise a bar magnet of magnetic intensity $2.4\times 10^3{\text{ Am}}^{-1}$ is ___________ A.

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   Answer: 6

8. Q422023 · 10 Apr 2023 · Shift 2

   Given below are two statements: Statement I : For diamagnetic substance, $-1\le \chi <0$, where $\chi$ is the magnetic susceptibility. Statement II : Diamagnetic substances when placed in an external magnetic field, tend to move from stronger to weaker part of the field. In the light of the above statements, choose the correct answer from the options given below

   1. A.Both Statement I and Statement II are true
   2. B.Statement I is correct but Statement II is false
   3. C.Both Statement I and Statement II are False
   4. D.Statement I is incorrect but Statement II is true.
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   Answer: A

9. Q522023 · 10 Apr 2023 · Shift 2· Numerical answer
   
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   Answer: 2

10. Q542023 · 10 Apr 2023 · Shift 2· Numerical answer

    A square loop of side 2.0 cm is placed inside a long solenoid that has 50 turns per centimetre and carries a sinusoidally varying current of amplitude 2.5 A and angular frequency $700{\text{ rad s}}^{-1}$. The central axes of the loop and solenoid coincide. The amplitude of the emf induced in the loop is $x\times 10^{-4}\text{ V}$. The value of x is _________. (Take, $\pi =\frac{22}{7}$)

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    Answer: 44

11. Q382023 · 8 Apr 2023 · Shift 1

    A charge particle moving in magnetic field $\mathrm{B}$, has the components of velocity along $\mathrm{B}$ as well as perpendicular to $\mathrm{B}$. The path of the charge particle will be

    1. A.helical path with the axis along magnetic field $\mathrm{B}$
    2. B.straight along the direction of magnetic field $\mathrm{B}$
    3. C.circular path
    4. D.helical path with the axis perpendicular to the direction of magnetic field $\mathrm{B}$
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    Answer: A

12. Q512023 · 8 Apr 2023 · Shift 1· Numerical answer

    The magnetic intensity at the center of a long current carrying solenoid is found to be $1.6\times 10^3{\text{Am}}^{-1}$. If the number of turns is $8$ per $\text{cm}$, then the current flowing through the solenoid is ___________ $\text{A}$.

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    Answer: 2

13. Q322023 · 8 Apr 2023 · Shift 2

    An emf of $0.08\text{ V}$ is induced in a metal rod of length $10\text{ cm}$ held normal to a uniform magnetic field of $0.4\text{ T}$, when moves with a velocity of:

    1. A.$20{\text{ ms}}^{-1}$
    2. B.$2{\text{ ms}}^{-1}$
    3. C.$3.2{\text{ ms}}^{-1}$
    4. D.$0.5{\text{ ms}}^{-1}$
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    Answer: B

14. Q582023 · 8 Apr 2023 · Shift 2· Numerical answer

    The ratio of magnetic field at the centre of a current carrying coil of radius $r$ to the magnetic field at distance $r$ from the centre of coil on its axis is $\sqrt{x}:1$. The value of $x$ is ____

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    Answer: 8

15. Q322023 · 6 Apr 2023 · Shift 1

    The induced emf can be produced in a coil by A. moving the coil with uniform speed inside uniform magnetic field B. moving the coil with non uniform speed inside uniform magnetic field C. rotating the coil inside the uniform magnetic field D. changing the area of the coil inside the uniform magnetic field Choose the correct answer from the options given below:

    1. A.A and C only
    2. B.C and D only
    3. C.B and D only
    4. D.B and C only
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    Answer: B

16. Q412023 · 6 Apr 2023 · Shift 1

    A long straight wire of circular cross-section (radius a) is carrying steady current I. The current I is uniformly distributed across this cross-section. The magnetic field is

    1. A.uniform in the region $r<a$ and inversely proportional to distance $r$ from the axis, in the region $r>a$
    2. B.zero in the region $r<a$ and inversely proportional to $r$ in the region $r>a$
    3. C.directly proportional to $r$ in the region $r<a$ and inversely proportional to $r$ in the region $r>a$
    4. D.inversely proportional to $r$ in the region $r<a$ and uniform throughout in the region $r>a$
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    Answer: C

17. Q542023 · 6 Apr 2023 · Shift 1· Numerical answer
    
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    Answer: 628

18. Q562023 · 6 Apr 2023 · Shift 2· Numerical answer

    A proton with a kinetic energy of $2.0\text{ eV}$ moves into a region of uniform magnetic field of magnitude $\frac{\pi }{2}\times 10^{-3}\text{ T}$. The angle between the direction of magnetic field and velocity of proton is $60^{\circ }$. The pitch of the helical path taken by the proton is _________ $\text{cm}$. (Take, mass of proton $=1.6\times 10^{-27}\text{ kg}$ and Charge on proton $=1.6\times 10^{-19}\text{C}$ ).

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    Answer: 40

19. Q352023 · 1 Feb 2023 · Shift 1
    
    1. A.$\frac{{\mu }_{0}i}{2r}\left(\frac{1}{2}+\frac{1}{2\pi }\right)$
    2. B.$\frac{{\mu }_{0}i}{2r}\left(1+\frac{2}{\pi }\right)$
    3. C.$\frac{{\mu }_{0}i}{2r}\left(\frac{1}{2}+\frac{1}{\pi }\right)$
    4. D.$\frac{{\mu }_{0}i}{2r}\left(1+\frac{1}{\pi }\right)$
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    Answer: A

20. Q522023 · 1 Feb 2023 · Shift 1· Numerical answer

    A charge particle of $2\mu \text{C}$ accelerated by a potential difference of $100\text{ V}$ enters a region of uniform magnetic field of magnitude $4\text{ mT}$ at right angle to the direction of field. The charge particle completes semicircle of radius $3\text{ cm}$ inside magnetic field. The mass of the charge particle is ________ $\times 10^{-18}\text{ kg}$

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    Answer: 144

21. Q322023 · 31 Jan 2023 · Shift 1

    A bar magnet with a magnetic moment $5.0{\text{ Am}}^2$ is placed in parallel position relative to a magnetic field of $0.4\text{ T}$. The amount of required work done in turning the magnet from parallel to antiparallel position relative to the field direction is ___________.

    1. A.zero
    2. B.$1\text{ J}$
    3. C.$2\text{ J}$
    4. D.$4\text{ J}$
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    Answer: D

22. Q422023 · 31 Jan 2023 · Shift 2

    A long conducting wire having a current I flowing through it, is bent into a circular coil of N turns. Then it is bent into a circular coil of $n$ turns. The magnetic field is calculated at the centre of coils in both the cases. The ratio of the magnetic field in first case to that of second case is :

    1. A.$N^2:n^2$
    2. B.$N:n$
    3. C.$n:N$
    4. D.$n^2:N^2$
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    Answer: A

23. Q432023 · 30 Jan 2023 · Shift 1

    The magnetic moments associated with two closely wound circular coils A and B of radius ${\mathrm{r}}_{\mathrm{A}}=10\mathrm{cm}$ and ${\mathrm{r}}_{\mathrm{B}}=20\mathrm{cm}$ respectively are equal if : (Where ${\mathrm{N}}_{\mathrm{A}},{\mathrm{I}}_{\mathrm{A}}$ and ${\mathrm{N}}_{\mathrm{B}},{\mathrm{I}}_{\mathrm{B}}$ are number of turns and current of A and B respectively)

    1. A.$4{\mathrm{N}}_{\mathrm{A}}{\mathrm{I}}_{\mathrm{A}}={\mathrm{N}}_{\mathrm{B}}{\mathrm{I}}_{\mathrm{B}}$
    2. B.$2{\mathrm{N}}_{\mathrm{A}}{\mathrm{I}}_{\mathrm{A}}={\mathrm{N}}_{\mathrm{B}}{\mathrm{I}}_{\mathrm{B}}$
    3. C.${\mathrm{N}}_{\mathrm{A}}=2{\mathrm{N}}_{\mathrm{B}}$
    4. D.${\mathrm{N}}_{\mathrm{A}}{\mathrm{I}}_{\mathrm{A}}=4{\mathrm{N}}_{\mathrm{B}}{\mathrm{I}}_{\mathrm{B}}$
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    Answer: D

24. Q432023 · 29 Jan 2023 · Shift 1
    
    1. A.
    2. B.
    3. C.
    4. D.
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    Answer: D

25. Q572023 · 29 Jan 2023 · Shift 1· Numerical answer

    A certain elastic conducting material is stretched into a circular loop. It is placed with its plane perpendicular to a uniform magnetic field B = 0.8 T. When released the radius of the loop starts shrinking at a constant rate of 2 $\mathrm{cm}{\mathrm{s}}^{-1}$. The induced emf in the loop at an instant when the radius of the loop is 10 cm will be ____ mV.

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    Answer: 10