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

2025 18 questions

1. Q492025 · 4 Apr 2025 · Shift 1· Numerical answer
   
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   Answer: 10

2. Q492025 · 4 Apr 2025 · Shift 2· Numerical answer

   A particle of charge $1.6\mu \mathrm{C}$ and mass $16\mu \mathrm{g}$ is present in a strong magnetic field of $6.28\mathrm{T}$ . The particle is then fired perpendicular to magnetic field. The time required for the particle to return to original location for the first time is ____ s. $(\pi =3.14)$

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   Answer: 0

3. Q472025 · 3 Apr 2025 · Shift 1· Numerical answer
   
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   Answer: 1

4. Q502025 · 3 Apr 2025 · Shift 1· Numerical answer

   A 4.0 cm long straight wire carrying a current of 8 A is placed perpendicular to a uniform magnetic field of strength 0.15 T . The magnetic force on the wire is ________mN .

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   Answer: 48

5. Q302025 · 3 Apr 2025 · Shift 2

   A magnetic dipole experiences a torque of $80\sqrt{3}\mathrm{N}\mathrm{m}$ when placed in uniform magnetic field in such a way that dipole moment makes angle of $60^{\circ }$ with magnetic field. The potential energy of the dipole is :

   1. A.$-40\sqrt{3}\mathrm{J}$
   2. B.$-80\mathrm{J}$
   3. C.$80\mathrm{J}$
   4. D.$-60\mathrm{J}$
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   Answer: B

6. Q452025 · 3 Apr 2025 · Shift 2

   Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A : If Oxygen ion $({\mathrm{O}}^{-2})$ and Hydrogen ion $({\mathrm{H}}^{+})$ enter normal to the magnetic field with equal momentum, then the path of ${\mathrm{O}}^{-2}$ ion has a smaller curvature than that of ${\mathrm{H}}^{+}$. Reason R : A proton with same linear momentum as an electron will form a path of smaller radius of curvature on entering a uniform magnetic field perpendicularly. In the light of the above statements, choose the correct answer from the options given below

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

7. Q272025 · 2 Apr 2025 · Shift 1

   A monochromatic light is incident on a metallic plate having work function $\varphi$. An electron, emitted normally to the plate from a point A with maximum kinetic energy, enters a constant magnetic field, perpendicular to the initial velocity of electron. The electron passes through a curve and hits back the plate at a point $B$. The distance between $A$ and $B$ is : (Given : The magnitude of charge of an electron is e and mass is $\mathrm{m}$, $\mathrm{h}$ is Planck's constant and c is velocity of light. Take the magnetic field exists throughout the path of electron)

   1. A.$\sqrt{2\mathrm{m}\left(\frac{\mathrm{h}c}{\lambda }-\varphi \right)}/eB$
   2. B.$\sqrt{8\mathrm{m}\left(\frac{\mathrm{h}c}{\lambda }-\varphi \right)}/eB$
   3. C.$\sqrt{\mathrm{m}(\mathrm{h}c/\lambda -\varphi )}/eB$
   4. D.$2\sqrt{\mathrm{m}(\mathrm{h}c/\lambda -\varphi )}/eB$
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   Answer: B

8. Q312025 · 2 Apr 2025 · Shift 1

   Let $B_1$ be the magnitude of magnetic field at center of a circular coil of radius $R$ carrying current I. Let $B_2$ be the magnitude of magnetic field at an axial distance ' $x$ ' from the center. For $x:R=3:4$, $\frac{B_2}{B_1}$ is :

   1. A.64 : 125
   2. B.25 : 16
   3. C.4 : 5
   4. D.16 : 25
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   Answer: A

9. Q412025 · 2 Apr 2025 · Shift 1

   The relationship between the magnetic susceptibility ($\chi$) and the magnetic permeability ($\mu$) is given by : ( ${\mu }_0$ is the permeability of free space and ${\mu }_r$ is relative permeability)

   1. A.$\chi =\frac{\mu }{{\mu }_0}-1$
   2. B.$\chi =\frac{{\mu }_r}{{\mu }_0}+1$
   3. C.$\chi ={\mu }_r+1$
   4. D.$\chi =1-\frac{\mu }{{\mu }_0}$
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   Answer: A

10. Q312025 · 2 Apr 2025 · Shift 2

    A solenoid having area A and length ' $l$ ' is filled with a material having relative permeability 2. The magnetic energy stored in the solenoid is :

    1. A.$\frac{{\mathrm{B}}^2\mathrm{Al}}{4{\mu }_0}$
    2. B.$\frac{{\mathrm{B}}^2\mathrm{Al}}{2{\mu }_0}$
    3. C.$\frac{{\mathrm{B}}^2\mathrm{Al}}{{\mu }_0}$
    4. D.${\mathrm{B}}^2\mathrm{Al}$
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    Answer: A

11. Q352025 · 2 Apr 2025 · Shift 2

    An electron with mass ' $\mathrm{m}$ ' with an initial velocity $(t=0)\vec{\mathrm{v}}={\mathrm{v}}_0\hat{i}({\mathrm{v}}_0>0)$ enters a magnetic field $\vec{\mathrm{B}}={\mathrm{B}}_0\hat{j}$. If the initial de-Broglie wavelength at $t=0$ is ${\lambda }_0$ then its value after time ' t ' would be :

    1. A.$\frac{{\lambda }_0}{\sqrt{1-\frac{e^2{\mathrm{B}}_0^2{t}^2}{{\mathrm{m}}^2}}}$
    2. B.${\lambda }_0$
    3. C.${\lambda }_0\sqrt{1+\frac{e^2{\mathrm{B}}_0^2{t}^2}{{\mathrm{m}}^2}}$
    4. D.$\frac{{\lambda }_0}{\sqrt{1+\frac{e^2{\mathrm{B}}_0^2{t}^2}{{\mathrm{m}}^2}}}$
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    Answer: B

12. Q372025 · 29 Jan 2025 · Shift 2

    Match List - I with List - II. $$\begin{array}{ll}\text{List - I}& \text{List - II}\\ \text{(A) Magnetic induction}& {\text{(I) Ampere meter}}^2\\ \text{(B) Magnetic intensity}& \text{(II) Weber}\\ \text{(C) Magnetic flux}& \text{(III) Gauss}\\ \text{(D) Magnetic moment}& {\text{(IV) Ampere meter}}^{-1}\end{array}$$ Choose the correct answer from the options given below:

    1. A.(A)-(III), (B)-(IV), (C)-(II), (D)-(I)
    2. B.(A)-(III), (B)-(II), (C)-(I), (D)-(IV)
    3. C.(A)-(III), (B)-(IV), (C)-(I), (D)-(II)
    4. D.(A)-(I), (B)-(II), (C)-(III), (D)-(IV)
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    Answer: A

13. Q502025 · 29 Jan 2025 · Shift 2· Numerical answer

    The magnetic field inside a 200 turns solenoid of radius $10\mathrm{cm}$ is $2.9\times 10^{-4}\mathrm{Tesla}$. If the solenoid carries a current of $0.29\mathrm{A}$ , then the length of the solenoid is ____ $\pi \mathrm{cm}$.

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    Answer: 8

14. Q472025 · 24 Jan 2025 · Shift 1· Numerical answer

    A current of $5\mathrm{A}$ exists in a square loop of side $\frac{1}{\sqrt{2}}\mathrm{m}$. Then the magnitude of the magnetic field $B$ at the centre of the square loop will be $p\times 10^{-6}\mathrm{T}$. where, value of p is ____ [ Take ${\mu }_0=4\pi \times 10^{-7}\mathrm{T}\mathrm{m}{\mathrm{A}}^{-1}$ ].

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    Answer: 8

15. Q282025 · 24 Jan 2025 · Shift 2

    Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : An electron in a certain region of uniform magnetic field is moving with constant velocity in a straight line path. Reason (R) : The magnetic field in that region is along the direction of velocity of the electron. 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.Both (A) and (R) are true and (R) is the correct explanation of (A)
    3. C.Both (A) and (R) are true but (R) is NOT the correct explanation of (A)
    4. D.(A) is false but (R) is true
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    Answer: B

16. Q342025 · 24 Jan 2025 · Shift 2
    
    1. A.
    2. B.
    3. C.
    4. D.
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    Answer: B

17. Q502025 · 24 Jan 2025 · Shift 2· Numerical answer

    A tightly wound long solenoid carries a current of 1.5 A . An electron is executing uniform circular motion inside the solenoid with a time period of 75 ns . The number of turns per metre in the solenoid is ________. [Take mass of electron ${\mathrm{m}}_e=9\times 10^{-31}\text{ kg}$, charge of electron $|{\mathrm{q}}_e|=1.6\times 10^{-19}\text{C}$, ${\mu }_0=4\pi \times 10^{-7}\frac{\mathrm{N}}{{\mathrm{A}}^2}$, $1\text{ ns}=10^{-9}\text{ s}$]

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    Answer: 250

18. Q422025 · 23 Jan 2025 · Shift 2

    Match List - I with List - II | | List - I | | List - II | |---|---|---|---| | (A) | Permeability of free space | (I) | $\left[{\mathrm{ML}}^2{\mathrm{T}}^{-2}\right]$ | | (B) | Magnetic field | (II) | $\left[{\mathrm{MT}}^{-2}{\mathrm{A}}^{-1}\right]$ | | (C) | Magnetic moment | (III) | $\left[{\mathrm{MLT}}^{-2}{\mathrm{A}}^{-2}\right]$ | | (D) | Torsional constant | (IV) | $\left[{\mathrm{L}}^2\mathrm{A}\right]$ | Choose the correct answer from the options given below :

    1. A.(A)-(III), (B)-(II), (C)-(IV), (D)-(I)
    2. B.(A) – (I), (B) – (IV), (C) – (II), (D) – (III)
    3. C.(A) – (II), (B) – (I), (C) – (III), (D) – (IV)
    4. D.(A)-(IV), (B)-(III), (C)-(I), (D)-(II)
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    Answer: A