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

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2021 19 questions

Q402021 · 1 Sept 2021 · Shift 2
1. A.(a), (c)
2. B.(a), (d)
3. C.(b), (d)
4. D.(b), (c)
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Answer: A
Q492021 · 1 Sept 2021 · Shift 2
1. A. $\frac{μ _{0} I}{4 π x y} [x^{2} + y^{2} + (x + y)]$
2. B. $\frac{μ _{0} I}{4 π x y} [x^{2} + y^{2} - (x + y)]$
3. C. $\frac{μ _{0} I x y}{4 π} [x^{2} + y^{2} - (x + y)]$
4. D. $\frac{μ _{0} I x y}{4 π} [x^{2} + y^{2} + (x + y)]$
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Answer: A
Q552021 · 26 Aug 2021 · Shift 2· Numerical answer
A circular coil of radius 8.0 cm and 20 turns is rotated about its vertical diameter with an angular speed of $50 rad s^{- 1}$ in a uniform horizontal magnetic field of $3.0 \times 1 0^{- 2} T$ . The maximum emf induced the coil will be ............... $\times 1 0^{- 2} volt$ (rounded off to the nearest integer)
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Answer: 60
Q412021 · 27 Jul 2021 · Shift 2
1. A.
2. B.
3. C.
4. D.
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Answer: C
Q562021 · 25 Jul 2021 · Shift 1· Numerical answer
The value of aluminium susceptibility is $2.2 \times 1 0^{- 5}$ . The percentage increase in the magnetic field if space within a current carrying toroid is filled with aluminium is $\frac{x}{1 0 ^{4}}$ . Then the value of x is ____.
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Answer: 22
Q352021 · 25 Jul 2021 · Shift 2
Two ions having same mass have charges in the ratio 1 : 2. They are projected normally in a uniform magnetic field with their speeds in the ratio 2 : 3. The ratio of the radii of their circular trajectories is :
1. A.1 : 4
2. B.4 : 3
3. C.3 : 1
4. D.2 : 3
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Answer: B
Q522021 · 25 Jul 2021 · Shift 2· Numerical answer
A light beam of wavelength 500 nm is incident on a metal having work function of 1.25 eV, placed in a magnetic field of intensity B. The electrons emitted perpendicular to the magnetic field B, with maximum kinetic energy are bent into circular arc of radius 30 cm. The value of B is ____ $\times 1 0^{- 7}$ T. Given hc = $20 \times 1 0^{- 26}$ J-m, mass of electron = $9 \times 1 0^{- 31}$ kg
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Answer: 125
Q362021 · 22 Jul 2021 · Shift 2
Intensity of sunlight is observed as $0.092 Wm^{- 2}$ at a point in free space. What will be the peak value of magnetic field at the point? ( $ε_{0} = 8.85 \times 1 0^{- 12} C^{2} N^{- 1} m^{- 2}$ )
1. A. $2.77 \times 1 0^{- 8} T$
2. B. $1.96 \times 1 0^{- 8} T$
3. C. $8.31 T$
4. D. $5.88 T$
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Answer: A
Q412021 · 22 Jul 2021 · Shift 2
Statement I : The ferromagnetic property depends on temperature. At high temperature, ferromagnet becomes paramagnet. Statement II : At high temperature, the domain wall area of a ferromagnetic substance increases. In the light of the above statements, choose the most appropriate answer from the options given below :
1. A.Statement I is false but Statement II is true
2. B.Statement I is true but Statement II is false
3. C.Both Statement I and Statement II are false
4. D.Both Statement I and Statement II are true
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Answer: B
Q312021 · 20 Jul 2021 · Shift 1
A deuteron and an alpha particle having equal kinetic energy enter perpendicularly into a magnetic field. Let $r_{d}$ and $r_{α}$ be their respective radii of circular path. The value of $\frac{r _{d}}{r _{α}}$ is equal to :
1. A. $1$
2. B. $2$
3. C. $2$
4. D. $\frac{1}{2}$
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Answer: C
Q392021 · 20 Jul 2021 · Shift 1
1. A.A-Flux, B-Power dissipated, C-EMF
2. B.A-Flux, B-EMF, C-Power dissipated
3. C.A-Power dissipated, B-Flux, C-EMF
4. D.A-EMF, B-Power dissipated, C-Flux
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Answer: B
Q432021 · 20 Jul 2021 · Shift 1
The radiation corresponding to $3 \to 2$ transition of a hydrogen atom falls on a gold surface to generate photoelectrons. The electrons are passed through a magnetic field of $5 \times 1 0^{- 4} T$ . Assume that the radius of the largest circular path followed by these electrons is $7 mm$ , the work function of the metal is : (Mass of electron $= 9.1 \times 1 0^{- 31} kg$ )
1. A. $1.36 eV$
2. B. $1.88 eV$
3. C. $0.82 eV$
4. D. $0.16 eV$
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Answer: C
Q352021 · 18 Mar 2021 · Shift 1
1. A.12T
2. B.6T
3. C.9T
4. D.1T
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Answer: D
Q442021 · 18 Mar 2021 · Shift 1
A loop of flexible wire of irregular shape carrying current is placed in an external magnetic field. Identify the effect of the field on the wire.
1. A.Loop assumes circular shape with its plane normal to the field.
2. B.Loop assumes circular shape with its plane parallel to the field.
3. C.Wire gets stretched to become straight.
4. D.Shape of the loop remains unchanged.
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Answer: A
Q452021 · 18 Mar 2021 · Shift 2
A proton and an $α$ -particle, having kinetic energies $K_{p}$ and $K_{α}$ respectively, enter into a magnetic field at right angles. The ratio of the radii of trajectory of proton to that of $α$ -particle is $2 : 1$ . The ratio of $K_{p} : K_{α}$ is :
1. A. $8 : 1$
2. B. $4 : 1$
3. C. $1 : 8$
4. D. $1 : 4$
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Answer: B
Q472021 · 18 Mar 2021 · Shift 2
Which of the following statements are correct? (A) Electric monopoles do not exist whereas magnetic monopoles exist. (B) Magnetic field lines due to a solenoid at its ends and outside cannot be completely straight and confined. (C) Magnetic field lines are completely confined within a toroid. (D) Magnetic field lines inside a bar magnet are not parallel. (E) $χ = - 1$ is the condition for a perfect diamagnetic material, where $χ$ is its magnetic susceptibility. Choose the correct answer from the options given below :
1. A.(A) and (B) only
2. B.(B) and (C) only
3. C.(C) and (E) only
4. D.(B) and (D) only
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Answer: C
Q472021 · 16 Mar 2021 · Shift 1
1. A.Both $I_{1}$ and $I_{2}$ are in clockwise direction
2. B. $I_{1}$ is in clockwise direction and $I_{2}$ is in anticlockwise direction
3. C. $I_{1}$ is in anticlockwise direction and $I_{2}$ is in clockwise direction
4. D.Both $I_{1}$ and $I_{2}$ are in anticlockwise direction
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Answer: B
Q502021 · 16 Mar 2021 · Shift 1
A bar magnet of length 14 cm is placed in the magnetic meridian with its north pole pointing towards the geographic north pole. A neutral point is obtained at a distance of 18 cm from the center of the magnet. If $B_{H} = 0.4 G$ , the magnetic moment of the magnet is : $(1 G = 1 0^{- 4} T)$
1. A. $2.880 \times 1 0^{2} J T^{- 1}$
2. B. $2.880 J T^{- 1}$
3. C. $2.880 \times 1 0^{3} J T^{- 1}$
4. D. $28.80 J T^{- 1}$
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Answer: B
Q362021 · 25 Feb 2021 · Shift 2
In a ferromagnetic material, below the curie temperature, a domain is defined as :
1. A.a macroscopic region with zero magnetization.
2. B.a macroscopic region with saturation magnetization.
3. C.a macroscopic region with randomly oriented magnetic dipoles.
4. D.a macroscopic region with consecutive magnetic dipoles oriented in opposite direction.
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Answer: B