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

2023 37 questions

1. 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

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

3. 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

4. Q352023 · 25 Jan 2023 · Shift 1
   
   1. A.A-III, B-IV, C-I, D-II
   2. B.A-II, B-I, C-IV, D-III
   3. C.A-III, B-I, C-IV, D-II
   4. D.A-I, B-III, C-IV, D-II
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   Answer: C

5. Q422023 · 25 Jan 2023 · Shift 1

   A solenoid of 1200 turns is wound uniformly in a single layer on a glass tube 2 m long and 0.2 m in diameter. The magnetic intensity at the center of the solenoid when a current of 2 A flows through it is :

   1. A.$1\mathrm{A}{\mathrm{m}}^{-1}$
   2. B.$2.4\times 10^{-3}\mathrm{A}{\mathrm{m}}^{-1}$
   3. C.$1.2\times 10^3\mathrm{A}{\mathrm{m}}^{-1}$
   4. D.$2.4\times 10^3\mathrm{A}{\mathrm{m}}^{-1}$
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   Answer: C

6. Q352023 · 25 Jan 2023 · Shift 2

   A wire of length 1m moving with velocity 8 m/s at right angles to a magnetic field of 2T. The magnitude of induced emf, between the ends of wire will be __________.

   1. A.20 V
   2. B.8 V
   3. C.16 V
   4. D.12 V
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   Answer: C

7. Q472023 · 25 Jan 2023 · Shift 2

   For a moving coil galvanometer, the deflection in the coil is 0.05 rad when a current of 10 mA is passes through it. If the torsional constant of suspension wire is $4.0\times 10^{-5}\mathrm{N}\mathrm{m}\mathrm{ra}{\mathrm{d}}^{-1}$, the magnetic field is 0.01T and the number of turns in the coil is 200, the area of each turn (in $\mathrm{c}{\mathrm{m}}^2$) is :

   1. A.1.5
   2. B.2.0
   3. C.0.5
   4. D.1.0
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   Answer: D

8. Q512023 · 25 Jan 2023 · Shift 2· Numerical answer

   Two long parallel wires carrying currents 8A and 15A in opposite directions are placed at a distance of 7 cm from each other. A point P is equidistant from both the wires such that the lines joining the point P to the wires are perpendicular to each other. The magnitude of magnetic field at P is ____ $\times 10^{-6}$ T. (Given : $\sqrt{2}=1.4$)

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   Answer: 68

9. Q382023 · 24 Jan 2023 · Shift 1

   A circular loop of radius $r$ is carrying current I A. The ratio of magnetic field at the center of circular loop and at a distance r from the center of the loop on its axis is :

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

10. Q402023 · 24 Jan 2023 · Shift 1

    A conducting circular loop of radius $\frac{10}{\sqrt{\pi }}\mathrm{cm}$ is placed perpendicular to a uniform magnetic field of $0.5\mathrm{T}$. The magnetic field is decreased to zero in $0.5\mathrm{s}$ at a steady rate. The induced emf in the circular loop at $0.25\mathrm{s}$ is :

    1. A.$\mathrm{emf}=10\mathrm{mV}$
    2. B.$\mathrm{emf}=5\mathrm{mV}$
    3. C.$\mathrm{emf}=100\mathrm{mV}$
    4. D.$\mathrm{emf}=1\mathrm{mV}$
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    Answer: A

11. Q332023 · 24 Jan 2023 · Shift 2

    A long solenoid is formed by winding $70\mathrm{turns}\mathrm{c}{\mathrm{m}}^{-1}$. If 2.0 A current flows, then the magnetic field produced inside the solenoid is ________ $({\mu }_0=4\pi \times 10^{-7}\mathrm{T}\mathrm{m}{\mathrm{A}}^{-1})$

    1. A.$88\times 10^{-4}\mathrm{T}$
    2. B.$1232\times 10^{-4}\mathrm{T}$
    3. C.$176\times 10^{-4}\mathrm{T}$
    4. D.$352\times 10^{-4}\mathrm{T}$
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    Answer: C

12. Q572023 · 24 Jan 2023 · Shift 2· Numerical answer

    A single turn current loop in the shape of a right angle triangle with sides 5 cm, 12 cm, 13 cm is carrying a current of 2 A. The loop is in a uniform magnetic field of magnitude 0.75 T whose direction is parallel to the current in the 13 cm side of the loop. The magnitude of the magnetic force on the 5 cm side will be $\frac{x}{130}\mathrm{N}$. The value of $x$ is ___________.

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    Answer: 9