Magnetism and matter questions with solutions

Showing 1–10 of 77 questions

• MCQdifficultMagnetism and matterproperties of magnetic substance

  An atom has completely filled electronic shells. Which statement best explains why its permanent magnetic moment is generally zero?

  Options

  • Option A

    Each electron has zero spin

  • Option B

    Orbital and spin magnetic moments of paired electrons cancel

  • Option C

    The nucleus prevents magnetic moment formation

  • Option D

    Its magnetic susceptibility must therefore be exactly zero

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• MCQeasyMagnetism and matterproperties of magnetic substance

  Which microscopic property is primarily responsible for paramagnetism?

  Options

  • Option A

    All electrons are paired and each atom has zero permanent magnetic moment

  • Option B

    Atoms or molecules possess permanent magnetic moments due to unpaired electrons, but these moments are randomly oriented without an external field

  • Option C

    All atomic moments form permanent aligned domains even without interactions

  • Option D

    The applied field always induces a magnetic moment opposite to itself

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• MCQdifficultMagnetism and matterproperties of magnetic substance

  For the core of a transformer operating under repeated alternating magnetisation, the preferred magnetic material should have:

  Options

  • Option A

    Large coercivity and a large hysteresis-loop area

  • Option B

    Small coercivity, high permeability and a small hysteresis-loop area

  • Option C

    Large retentivity and very large coercivity

  • Option D

    Negative magnetic susceptibility

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

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

  A magnetic dipole executes angular motion in a uniform magnetic field. It is released from rest from an initial angular displacement θ₀ from the stable equilibrium position.

  Which statement is correct?

  Options

  • Option A

    The motion is exactly SHM for every θ₀

  • Option B

    The motion is SHM only for sufficiently small θ₀

  • Option C

    Its exact time period is independent of amplitude

  • Option D

    The restoring torque is exactly proportional to θ for all θ

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

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

  A bar magnet with a magnetic moment 5.0 A m² is placed in parallel position relative to a magnetic field of 0.4 T. The amount of required work done in turning the magnet from parallel to antiparallel position relative to the field direction is:

  Options

  • Option A

    4 J

  • Option B

    1 J

  • Option C

    2 J

  • Option D

    Zero

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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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• MCQdifficultMagnetism and matterproperties of magnetic substance

  Consider the following statements: I. Diamagnetism arises from an induced magnetic moment opposite to the applied field. II. Paramagnetic atoms generally possess permanent magnetic moments, but thermal agitation tends to randomise them. III. Ferromagnetism involves cooperative alignment associated with exchange interaction and magnetic domains. IV. Above the Curie temperature, a ferromagnet generally loses spontaneous ferromagnetic ordering. Which option is correct?

  Options

  • Option A

    I and II only

  • Option B

    II and III only

  • Option C

    I, II and III only

  • Option D

    I, II, III and IV

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• NumericmediumMagnetism and matterpole stength ,magnetic moment and magnetic field due to magnet

  The magnetic potential due to a magnetic dipole at a point on its axis situated at a distance of 20 cm from its center is 1.5 × 10⁻⁵ Tm. The magnetic moment of the dipole is__________ Am². (Given : μ₀/4π = 10⁻⁷ TmA⁻¹)

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