Question

At a given place on the Earth, a bar magnet of magnetic moment m is kept horizontal in the East-West direction. P and O are the two neutral points due to magnetic field of this magnet and Bh is the horizontal component of the Earth's magnetic field. (A) Calculate the angles between position vectors of P and Q with the direction of m (B) Points P and Q are 1 m from the centre of the bar magnet and Bh 3.5x 10 T. Calculate magnetic dipole moment of the bar magnet. Neutral point is that point where the resultant magnetic field is zero​

Answer 1

Explanation:

Correct option is

D

9.7

Magnetic field due to bar magnet of pole strength of m is given as at equatorial position is given as

B

=

4π

μ

∘

r

3

m

r is distance from middle point of magnet

r= 30 cm= .3 m;

4π

μ

∘

=10

−7

At neutral point the magnetic field of earth and bar magnet will be equal and opposite, the net magnetic field will be zero at neutral points.

B

magnet

=

B

earth

=10

−7

.3

3

m

B

earth

=B

H

from diagram

⇒m=

10

−

7

3.6×10

−

5×.3

3

m=9.72 A-m

solution