Magnetism and Matter physics questions with solutions

Showing 1–10 of 19 questions

• MCQmediumMagnetism and matterMagnetic Dipole in a Uniform Magnetic Field: Torque, Potential Energy and Oscillations

  A magnetic dipole of moment M is rotated slowly in a uniform magnetic field B from θ=30° to θ=120°, where θ is the angle between $\vec{M}$ and $\vec{B}$.

  The increase in its magnetic potential energy is:

  Options

  • Option A

    (√3+1)MB/2

  • Option B

    (√3-1)MB/2

  • Option C

    MB/2

  • Option D

    √3MB

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• MCQmediumMagnetism and matterMagnetic Dipole in a Uniform Magnetic Field: Torque, Potential Energy and Oscillations

  A thin bar magnet has magnetic length L and magnetic moment M. It is bent uniformly into a semicircular arc without changing its pole strength.

  Its new magnetic moment is:

  Options

  • Option A

    M/π

  • Option B

    2M/π

  • Option C

    πM/2

  • Option D

    M/2

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• MCQdifficultMagnetism and matterMagnetic Dipole in a Uniform Magnetic Field: Torque, Potential Energy and Oscillations

  A thin magnet of original magnetic moment M is bent sharply at its midpoint. After bending, the magnetic-moment vectors associated with the two equal halves make an angle 2α with each other. Pole strength and the magnetic moment magnitude of each half remain unchanged.

  The magnitude of the resultant magnetic moment is:

  Options

  • Option A

    M sinα

  • Option B

    M cosα

  • Option C

    2M cosα

  • Option D

    M√[2(1+cos2α)]

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• MCQdifficultMagnetism and matterMagnetic Dipole in a Uniform Magnetic Field: Torque, Potential Energy and Oscillations

  A magnetic dipole of moment M and moment of inertia I is initially at rest at an angular displacement 60° from its stable equilibrium position in a uniform magnetic field B.

  When it passes through the angular position 30°, its angular speed is:

  Options

  • Option A

    √[MB(√3-1)/I]

  • Option B

    √[MB(√3-1)/(2I)]

  • Option C

    √[2MB(√3-1)/I]

  • Option D

    √(MB/I)

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• MCQeasyMagnetism and matterMagnetic Dipole in a Uniform Magnetic Field: Torque, Potential Energy and Oscillations

  A magnet performs small angular oscillations in a uniform magnetic field B with time period T. Its magnetic moment is doubled without changing its moment of inertia.

  The new time period is:

  Options

  • Option A

    T/2

  • Option B

    T/√2

  • Option C

    √2T

  • Option D

    2T

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• MCQeasyMagnetism and matterMagnetic Dipole in a Uniform Magnetic Field: Torque, Potential Energy and Oscillations

  A magnet oscillates in Earth's horizontal magnetic field $B_H$ with time period T. At the same place, a uniform horizontal external magnetic field of magnitude 3$B_H$ is applied parallel to Earth's field.

  The new time period is:

  Options

  • Option A

    T/2

  • Option B

    T/√3

  • Option C

    2T

  • Option D

    T/4

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• MCQmediumMagnetism and matterMagnetic Dipole in a Uniform Magnetic Field: Torque, Potential Energy and Oscillations

  A magnet of magnetic moment M and moment of inertia I oscillates with time period T in a uniform magnetic field B. It is replaced by another magnet having magnetic moment 4M and moment of inertia 9I.

  The time period of the new magnet is:

  Options

  • Option A

    3T/2

  • Option B

    3T/4

  • Option C

    2T/3

  • Option D

    3T

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• MCQmediumMagnetism and matterMagnetic Dipole in a Uniform Magnetic Field: Torque, Potential Energy and Oscillations

  Two identical short bar magnets, each of magnetic moment M, are placed coaxially with their centres separated by distance r, where r is much larger than their lengths. Like poles face each other.

  The magnitude of force between the magnets is:

  Options

  • Option A

    3μ₀M²/(2πr⁴)

  • Option B

    μ₀M²/(2πr⁴)

  • Option C

    3μ₀M²/(4πr⁴)

  • Option D

    μ₀M²/(4πr⁴)

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• MCQdifficultMagnetism and matterMagnetic Dipole in a Uniform Magnetic Field: Torque, Potential Energy and Oscillations

  A magnetic dipole of moment M and moment of inertia I is initially held at 120° to a uniform magnetic field B and released from rest. Neglect friction.

  Its maximum angular speed is:

  Options

  • Option A

    √(MB/I)

  • Option B

    √(2MB/I)

  • Option C

    √(3MB/I)

  • Option D

    2√(MB/I)

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• MCQeasyMagnetism and matterMagnetic Dipole in a Uniform Magnetic Field: Torque, Potential Energy and Oscillations

  A magnetic dipole in a uniform magnetic field B has magnetic potential energy

  U = -MB/2.

  The magnitude of torque acting on it is:

  Options

  • Option A

    √3MB/2

  • Option B

    MB/2

  • Option C

    MB

  • Option D

    MB/√2

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