Magnetism and Matter physics questions with solutions

Showing 1–10 of 19 questions

• MCQdifficultMagnetism and mattermagnet in magnetic field, torque, potential energy, oscillation and magnetic moment

  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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• MCQeasyMagnetism and mattermagnet in magnetic field, torque, potential energy, oscillation and magnetic moment

  A magnetic dipole of moment M is slowly rotated from its stable equilibrium orientation to its unstable equilibrium orientation in a uniform magnetic field B.

  The minimum external work required is:

  Options

  • Option A

    MB

  • Option B

    2MB

  • Option C

    MB/2

  • Option D

    4MB

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• MCQdifficultMagnetism and mattermagnet in magnetic field, torque, potential energy, oscillation and magnetic moment

  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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• MCQmediumMagnetism and mattermagnet in magnetic field, torque, potential energy, oscillation and magnetic moment

  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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• MCQeasyMagnetism and mattermagnet in magnetic field, torque, potential energy, oscillation and magnetic moment

  A magnetic dipole of moment M is placed exactly antiparallel to a uniform magnetic field B.

  Which statement is correct?

  Options

  • Option A

    It is in stable equilibrium

  • Option B

    It is in unstable equilibrium

  • Option C

    The torque is maximum

  • Option D

    Its potential energy is minimum

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• MCQmediumMagnetism and mattermagnet in magnetic field, torque, potential energy, oscillation and magnetic moment

  A thin bar magnet of magnetic length L and original magnetic moment M is uniformly bent into a circular arc that subtends an angle φ at the centre, where φ is measured in radians.

  Its new magnetic moment is:

  Options

  • Option A

    M·2sin(φ/2)/φ

  • Option B

    M·sinφ/φ

  • Option C

    M·φ/[2sin(φ/2)]

  • Option D

    M cos(φ/2)

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• MCQeasyMagnetism and mattermagnet in magnetic field, torque, potential energy, oscillation and magnetic moment

  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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• MCQeasyMagnetism and mattermagnet in magnetic field, torque, potential energy, oscillation and magnetic moment

  A magnet oscillates in Earth's horizontal magnetic field $B_H$ with time period T. An external horizontal field of magnitude 3$B_H/4$ is then applied opposite to Earth's horizontal field.

  The new time period is:

  Options

  • Option A

    2T

  • Option B

    T/2

  • Option C

    √2T

  • Option D

    4T

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• MCQmediumMagnetism and mattermagnet in magnetic field, torque, potential energy, oscillation and magnetic moment

  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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• MCQeasyMagnetism and mattermagnet in magnetic field, torque, potential energy, oscillation and magnetic moment

  A bar magnet of magnetic moment M and moment of inertia I is suspended freely in a uniform horizontal magnetic field B. It is displaced through a small angle from its stable equilibrium position and released.

  Its time period of small angular oscillations is:

  Options

  • Option A

    2π√(I/MB)

  • Option B

    2π√(MB/I)

  • Option C

    π√(I/MB)

  • Option D

    2π√(I/2MB)

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