31.

Assertion:  A superconductor is a perfect diamagnetic substance.

Reason:  superconductor is a perfect conductor.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Which of the following subsances magnetic susceptibility χ_m is negative?

• Diamagnetic

• Paramagnetic

• Ferromagnetic

• antiferromagnetic

When orientation. of dipoles parallel and antiparallel to magnetic field is distributed unequally, then the material is

• paramagnetic

• ferromagnetic

• ferrimagnetic

• antiferromagnetic

Which of the following is true regarding diamagnetic substaces symbols ( symbols have their usual meaning)

• μ > 1, χ_m > 1

• μ > 1, χ_m < 1

• μ_r < 1, χ_m < 1

• μ >1, χ_m < 1

Assertion: The magnetic poles of earth do not coincide with the geographic poles. 

Reason:  The discrepancy between the orientation of a compass and true north-south direction is known as magnetic declination.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

A  current  I₁  carrying  wire  AB  is  placed  near  another   long  wire  CD  carrying  current I₂. If  wire  AB  is  free  to  move,  it  will  have

• rotational motion only

• translational motion only

• rotational as well as translational motion

• neither rotational nor translational motion

Assertion: Magnetic susceptibillity is a pure number. 

Reason: The value of magnetic susceptibility for vacuum is one.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Lumen is the unit of

• Luminous flux

• luminosity

• illumination

• quantity of light

Assertion: We cannot think of magnetic field configuration with three poles.

Reason: A bar magnet does exert a torque on itself to its own field.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

Assertion:  The energy of charged particle moving in a uniform magnetic field does not change. 

Reason: Work done by magnetic field on the charge is zero

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false