Magnetism & Matter

A bar magnet has pole strength 10 A·m and effective length 10 cm. What is its magnetic moment?

Two magnetic poles, each of pole strength 10 A·m, are placed 10 cm apart in air. What is the force between them?

A bar magnet has a geometric length of 24 cm. What is its effective (magnetic) length?

A short bar magnet of magnetic moment 2 A·m² is placed with its axis along the line joining it to a point P, 20 cm away from its centre (P far from the magnet). What is the magnetic field at P?

A short bar magnet of magnetic moment 1 A·m² has a point Q on its equatorial line, 10 cm from its centre (Q far from the magnet). What is the magnetic field at Q?

A bar magnet of moment 4 A·m² produces a field B₁ at an axial point 10 cm from its centre, and a field B₂ at an equatorial point at the same distance (both points far from the magnet). What is B₁ : B₂?

A magnetic dipole of moment 5 A·m² is placed in a uniform field of 0.2 T, with its moment making an angle of 30° with the field. What is the torque on it?

A magnetic dipole of moment 4 A·m² is placed in a uniform field of 0.5 T, with its moment at 60° to the field. What is its potential energy?

A magnetic dipole of moment 3 A·m² is rotated from being parallel to a uniform field of 0.4 T to being exactly antiparallel to it. How much work is done?

A magnetic dipole is free to rotate in a uniform magnetic field. In which orientation is its potential energy minimum, and is that orientation stable or unstable?

At a place, the Earth's total magnetic field is 6 × 10⁻⁵ T and the angle of dip is 60°. What is the horizontal component of the field?

At a certain place, the horizontal component of Earth's field is √3 × 10⁻⁵ T and the vertical component is 1 × 10⁻⁵ T. What is the angle of dip at this place?

The true angle of dip at a place is 45°. A dip circle is set up at 60° to the magnetic meridian. What apparent dip will it show?

A tangent galvanometer has 50 turns of radius 20 cm. If the horizontal component of Earth's field is 3 × 10⁻⁵ T, what current produces a deflection of 45°?

A tangent galvanometer shows a deflection of 30° for a current of 0.1 A. What is its reduction factor?

Two identical bar magnets (same size and moment of inertia) are vibrated one at a time in a vibration magnetometer, giving time periods 2 s and 4 s respectively. What is the ratio of their magnetic moments M₁/M₂ (magnet 1 vibrated in T₁ = 2 s)?

A short bar magnet of moment 10 A·m² is placed with its south pole pointing towards geographic north. If the horizontal component of Earth's field is 4 × 10⁻⁵ T, find the distance of the neutral points from the magnet's centre (along its axis).

A magnetic material has a susceptibility of 1499. What is its relative permeability?