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1.

Magnetic moment of a magnetic dipole: M = m × 2 l where m = pole strength of the dipole. 2l = magnetic length of the dipole. Direction of is from south pole to north pole.

2.

Magnetic induction ( ) at a point P at a distance of 'r' from centre of a short magnetic dipole:

B =

m_{0}

4p

(in magnitude)

Where

m_{0} = permeability of free space M = Magnetic dipole moment of the dipole q = angle between the line joining point P and the centre of the dipole and axis of the dipole.

Direction of at P is given by,

tan f =

1

2

tan q

The angle made by with axis of the dipole = f + q

Case I: If P is a point on the axis of the dipole, q = 0° or q = 180°

\ B_{axis} =

2M

r^{3}

; direction along the axis, parallel to

Case II: If P is a point on the equator of the dipole, q = 90°

\ B_{equator} =

; direction parallel to the axis and opposite to .

3.

Magnetic potential (V) at a point P at a distance r from the centre of a short magnetic dipole is given by,

V =

M cos q

r^{2}

m_{0} = permeability of free space M = Magnetic dipole moment q = angle between the line passing through P and the centre of the dipole (O) and the axis of the dipole.

Case I:

If P is a point on axis, q = 0° or q = 180°

V_{axis} =

M

(for q = 0°)

Or

V_{axis} = -

(for q = 180°)

Case II:

If P is a point on equator, q = 90° \ V_{equator} = 0