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

2022 31 questions

1. Q562022 · 29 Jul 2022 · Shift 1· Numerical answer

   A closely wound circular coil of radius $5\mathrm{cm}$ produces a magnetic field of $37.68\times 10^{-4}\mathrm{T}$ at its center. The current through the coil is ____ $\mathrm{A}$. [Given, number of turns in the coil is 100 and $\pi =3.14$]

   Show answer

   Answer: 3

2. Q582022 · 29 Jul 2022 · Shift 1· Numerical answer

   A wire of length $314\mathrm{cm}$ carrying current of $14\mathrm{A}$ is bent to form a circle. The magnetic moment of the coil is ____ $\mathrm{A}-{\mathrm{m}}^2$. [Given $\pi =3.14$]

   Show answer

   Answer: 11

3. Q502022 · 29 Jul 2022 · Shift 2

   The vertical component of the earth's magnetic field is $6\times 10^{-5}\mathrm{T}$ at any place where the angle of dip is $37^{\circ }$. The earth's resultant magnetic field at that place will be (Given $\tan 37^{\circ }=\frac{3}{4}$)

   1. A.$8\times 10^{-5}\mathrm{T}$
   2. B.$6\times 10^{-5}\mathrm{T}$
   3. C.$5\times 10^{-4}\mathrm{T}$
   4. D.$1\times 10^{-4}\mathrm{T}$
   Show answer

   Answer: D

4. Q412022 · 28 Jul 2022 · Shift 1

   The current sensitivity of a galvanometer can be increased by : (A) decreasing the number of turns (B) increasing the magnetic field (C) decreasing the area of the coil (D) decreasing the torsional constant of the spring Choose the most appropriate answer from the options given below :

   1. A.(B) and (C) only
   2. B.(C) and (D) only
   3. C.(A) and (C) only
   4. D.(B) and (D) only
   Show answer

   Answer: D

5. Q422022 · 28 Jul 2022 · Shift 1
   
   1. A.$30\text{ A}$
   2. B.$15\text{ A}$
   3. C.$10\text{ A}$
   4. D.$3\text{ A}$
   Show answer

   Answer: A

6. Q422022 · 28 Jul 2022 · Shift 2
   
   1. A.$0.126\text{ N}$
   2. B.$0.312\text{ N}$
   3. C.$0.216\text{ N}$
   4. D.$0.245\text{ N}$
   Show answer

   Answer: C

7. Q432022 · 28 Jul 2022 · Shift 2

   The magnetic field at the center of current carrying circular loop is $B_1$. The magnetic field at a distance of $\sqrt{3}$ times radius of the given circular loop from the center on its axis is $B_2$. The value of $B_1/B_2$ will be

   1. A.$9:4$
   2. B.$12:\sqrt{5}$
   3. C.$8:1$
   4. D.$5:\sqrt{3}$
   Show answer

   Answer: C

8. Q472022 · 27 Jul 2022 · Shift 1

   Two bar magnets oscillate in a horizontal plane in earth's magnetic field with time periods of $3\text{ s}$ and $4\text{ s}$ respectively. If their moments of inertia are in the ratio of $3:2$, then the ratio of their magnetic moments will be:

   1. A.$2:1$
   2. B.$8:3$
   3. C.$1:3$
   4. D.$27:16$
   Show answer

   Answer: B

9. Q412022 · 27 Jul 2022 · Shift 2

   A cyclotron is used to accelerate protons. If the operating magnetic field is $1.0\mathrm{T}$ and the radius of the cyclotron 'dees' is $60\mathrm{cm}$, the kinetic energy of the accelerated protons in $\mathrm{MeV}$ will be : $[\text{use }{\mathrm{m}}_{\mathrm{p}}=1.6\times 10^{-27}\mathrm{kg},\mathrm{e}=1.6\times 10^{-19}\mathrm{C}]$

   1. A.$12$
   2. B.$18$
   3. C.$16$
   4. D.$32$
   Show answer

   Answer: B

10. Q472022 · 27 Jul 2022 · Shift 2

    A compass needle of oscillation magnetometer oscillates 20 times per minute at a place $\mathrm{P}$ of dip $30^{\circ }$. The number of oscillations per minute become 10 at another place $\mathrm{Q}$ of $60^{\circ }$ dip. The ratio of the total magnetic field at the two places $(B_Q:B_P)$ is :

    1. A.$\sqrt{3}:4$
    2. B.$4:\sqrt{3}$
    3. C.$\sqrt{3}:2$
    4. D.$2:\sqrt{3}$
    Show answer

    Answer: A

11. Q542022 · 27 Jul 2022 · Shift 2· Numerical answer

    A conducting circular loop is placed in $X-Y$ plane in presence of magnetic field $\vec{\mathrm{B}}=\left(3t^3\hat{j}+3t^2\hat{k}\right)$ in SI unit. If the radius of the loop is $1\mathrm{m}$, the induced emf in the loop, at time, $t=2\mathrm{s}$ is $n\pi \mathrm{V}$. The value of $n$ is ____.

    Show answer

    Answer: 12

12. Q362022 · 26 Jul 2022 · Shift 1

    A charge particle is moving in a uniform magnetic field $(2\hat{i}+3\hat{j})\mathrm{T}$. If it has an acceleration of $(\alpha \hat{i}-4\hat{j})m/{\mathrm{s}}^2$, then the value of $\alpha$ will be :

    1. A.3
    2. B.6
    3. C.12
    4. D.2
    Show answer

    Answer: B

13. Q372022 · 26 Jul 2022 · Shift 1

    ${\mathrm{B}}_X$ and ${\mathrm{B}}_Y$ are the magnetic fields at the centre of two coils X and Y respectively each carrying equal current. If coil $X$ has 200 turns and $20\mathrm{cm}$ radius and coil $Y$ has 400 turns and $20\mathrm{cm}$ radius, the ratio of $B_X$ and $B_Y$ is :

    1. A.$1:1$
    2. B.$1:2$
    3. C.$2:1$
    4. D.$4:1$
    Show answer

    Answer: B

14. Q382022 · 25 Jul 2022 · Shift 2

    Light wave travelling in air along x-direction is given by $E_y=540\sin \pi \times 10^4(x-ct){\text{ Vm}}^{-1}$. Then, the peak value of magnetic field of wave will be (Given $c=3\times 10^8{\text{ ms}}^{-1}$)

    1. A.$18\times 10^{-7}\text{ T}$
    2. B.$54\times 10^{-7}\text{ T}$
    3. C.$54\times 10^{-8}\text{ T}$
    4. D.$18\times 10^{-8}\text{ T}$
    Show answer

    Answer: A

15. Q492022 · 25 Jul 2022 · Shift 2

    An electron with energy $0.1\text{ keV}$ moves at right angle to the earth's magnetic field of $1\times 10^{-4}{\text{ Wbm}}^{-2}$. The frequency of revolution of the electron will be : (Take mass of electron $=9.0\times 10^{-31}\text{ kg}$)

    1. A.$1.6\times 10^5\text{ Hz}$
    2. B.$5.6\times 10^5\text{ Hz}$
    3. C.$2.8\times 10^6\text{ Hz}$
    4. D.$1.8\times 10^6\text{ Hz}$
    Show answer

    Answer: C

16. Q392022 · 30 Jun 2022 · Shift 1

    A coil of n number of turns wound tightly in the form of a spiral with inner and outer radii $r_1$ and $r_2$ respectively. When a current of strength I is passed through the coil, the magnetic field at its centre will be :

    1. A.$\frac{{\mu }_{0}nI}{2(r_2-r_1)}$
    2. B.$\frac{{\mu }_{0}nI}{r_2}$
    3. C.$\frac{{\mu }_{0}nI}{r_2-r_1}{\log }_{\mathrm{e}}\frac{r_1}{r_2}$
    4. D.$\frac{{\mu }_{0}nI}{2(r_2-r_1)}{\log }_{\mathrm{e}}\frac{r_2}{r_1}$
    Show answer

    Answer: D

17. Q422022 · 28 Jun 2022 · Shift 2

    The space inside a straight current carrying solenoid is filled with a magnetic material having magnetic susceptibility equal to $1.2\times 10^{-5}$. What is fractional increase in the magnetic field inside solenoid with respect to air as medium inside the solenoid?

    1. A.$1.2\times 10^{-5}$
    2. B.$1.2\times 10^{-3}$
    3. C.$1.8\times 10^{-3}$
    4. D.$2.4\times 10^{-5}$
    Show answer

    Answer: A

18. Q442022 · 28 Jun 2022 · Shift 2

    A coil is placed in a time varying magnetic field. If the number of turns in the coil were to be halved and the radius of wire doubled, the electrical power dissipated due to the current induced in the coil would be : (Assume the coil to be short circuited.)

    1. A.Halved
    2. B.Quadrupled
    3. C.The same
    4. D.Doubled
    Show answer

    Answer: D

19. Q402022 · 27 Jun 2022 · Shift 1

    The susceptibility of a paramagnetic material is 99. The permeability of the material in $Wb/A\text{-}\mathrm{m}$, is : [Permeability of free space ${\mu }_0=4\pi \times 10^{-7}Wb/A\text{-}\mathrm{m}$]

    1. A.$4\pi \times 10^{-7}$
    2. B.$4\pi \times 10^{-4}$
    3. C.$4\pi \times 10^{-5}$
    4. D.$4\pi \times 10^{-6}$
    Show answer

    Answer: C

20. Q582022 · 27 Jun 2022 · Shift 2· Numerical answer

    A deuteron and a proton moving with equal kinetic energy enter into a uniform magnetic field at right angle to the field. If $r_d$ and $r_p$ are the radii of their circular paths respectively, then the ratio $\frac{r_d}{r_p}$ will be $\sqrt{x}:1$ where x is ________.

    Show answer

    Answer: 2

21. Q592022 · 27 Jun 2022 · Shift 2· Numerical answer

    A metallic rod of length $20\text{ cm}$ is placed in North-South direction and is moved at a constant speed of $20\text{ m/s}$ towards East. The horizontal component of the Earth's magnetic field at that place is $4\times 10^{-3}\text{ T}$ and the angle of dip is $45^{\circ }$. The emf induced in the rod is ________ mV.

    Show answer

    Answer: 16

22. Q432022 · 26 Jun 2022 · Shift 1

    A proton and an alpha particle of the same velocity enter in a uniform magnetic field which is acting perpendicular to their direction of motion. The ratio of the radii of the circular paths described by the alpha particle and proton is :

    1. A.1 : 4
    2. B.4 : 1
    3. C.2 : 1
    4. D.1 : 2
    Show answer

    Answer: C

23. Q422022 · 26 Jun 2022 · Shift 2

    A bar magnet having a magnetic moment of $2.0\times 10^5{\text{ JT}}^{-1}$, is placed along the direction of uniform magnetic field of magnitude $\mathrm{B}=14\times 10^{-5}\text{ T}$. The work done in rotating the magnet slowly through $60^{\circ }$ from the direction of field is :

    1. A.14 J
    2. B.8.4 J
    3. C.4 J
    4. D.1.4 J
    Show answer

    Answer: A

24. Q442022 · 26 Jun 2022 · Shift 2

    A metallic conductor of length 1 m rotates in a vertical plane parallel to east-west direction about one of its end with angular velocity $5{\text{ rad s}}^{-1}$. If the horizontal component of earth's magnetic field is $0.2\times 10^{-4}\text{ T}$, then emf induced between the two ends of the conductor is :

    1. A.$5\mu \text{V}$
    2. B.$50\mu \text{V}$
    3. C.5 mV
    4. D.50 mV
    Show answer

    Answer: B

25. Q472022 · 26 Jun 2022 · Shift 2

    A metal surface is illuminated by a radiation of wavelength $4500\text{A˚}$. The ejected photo-electron enters a constant magnetic field of 2 mT making an angle of $90^{\circ }$ with the magnetic field. If it starts revolving in a circular path of radius 2 mm, the work function of the metal is approximately :

    1. A.1.36 eV
    2. B.1.69 eV
    3. C.2.78 eV
    4. D.2.23 eV
    Show answer

    Answer: A