AIIMS Physics Magnetism And Matter Class 12 Questions

At the magnetic poles of earth, only vertical component of earth's field exists and the horizontal component is zero. Hence, as compass needle is free to rotate in horizontal plane, it will affected by horizontal component only as H=0, Hence, the dip needle will stand vertical at the north pole of earth.

Assertion: Ferromagnetic compound is more attracted in magnetic field. Reason: Because all electron are aligned in same direction.

If the magnetizing field on a ferromagnetic material is increased, its permeability

Assertion: The magnetism of the magnet is due to the spin motion of electron. Reason: The dipole moment of electron is smaller than that due to orbit motion around nucleus.

If the magnetizing field on a ferromagnetic material is increased, its permeability:

Assertion: A planar circular loop of area A and carrying current I is equivalent to magnetic dipole of dipole moment M = IA. Reason: At large distances, magnetic field of circular loop and magnetic dipole is same.

Assertion: A superconductor is a perfect diamagnetic substance. Reason: A superconductor is a perfect conductor.

Which of the following substances magnetic susceptibility χm is negative?

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

Assertion : Magnetic field lines are continuous and closed. Reason : Magnetic monopole does not exist.

Assertion : Magnetic force between two short magnets, when they are co-axial follows inverse square law of distance. Reason : The magnetic forces between two poles do not follow inverse square law of distance.

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

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.

Assertion : Magnetic susceptibility is a pure number. Reason : The value of magnetic susceptibility for vacuum is one.

The magnetic susceptibility of an ideal diamagnetic substance is

Assertion : A current continues to follow in superconducting coil even after switch is off. Reason : Superconducting coils show Meissner effect.

Assertion : Ferro magnetic substances become paramagnetic above Curie temp. Reason : Domains are destroyed at high temp.

The magnetic moment has dimensions of

Assertion : Diamagnetic materials can exhibit magnetism. Reason : Diamagnetic materials have permanent magnetic dipole moment.

The Magnetic Resonance Imaging (MRI) is based on the phenomenon of

Liquid oxygen remains suspended between two pole faces of a magnet because it is

The magnetic moment of a current (I) carrying circular coil of radius (r) and number of turns (n) varies as

Assertion : The true geographic north direction is found by using a compass needle. Reason : The magnetic meridian of the earth is along the axis of rotation of the earth.

The earth's magnetic field at a given point is 0.5 × 10⁻⁵ Wb/m². This field is to be annulled by magnetic induction at the center of a circular conducting loop of radius 5.0 cm. The current required to be flown in the loop is nearly

A frog can be levitated in a magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as

Assertion : In high latitudes one sees colourful curtains of light hanging down from high altitudes. Reason : The high energy charged particles from the sun are deflected to polar regions by the magnetic field of the earth.

Assertion : We cannot think of a magnetic field configuration with three poles. Reason : A bar magnet does exert a torque on itself due to its own field.

Force between two identical bar magnets whose centres are r metre apart is 4.8 N when their axes are in the same line. If separation is increased to 2r, the force between them is reduced to