Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 12

# Is Placed Horizontally with the North Pole Pointing Towards East. Find the Position of the Neutral Point If the Horizontal Component of the Earth'S Magnetic Field is 18 μT. - Physics

Sum

A magnetic dipole of magnetic moment 0.72sqrt(2) "Am"^2 is placed horizontally with the north pole pointing towards east. Find the position of the neutral point if the horizontal component of the earth's magnetic field is 18 μT.

#### Solution

Given :
Magnetic moment of magnetic dipole,M = 0.72sqrt(2)  "A-m"^2

Horizontal component of the earth's magnetic field,B_H = 18  "uT"

Let d be the distance of neutral point from the dipole.

Magnetic field due to the bar magnet (B) on the equatorial line of the dipole is given by,

B = (u_0)/(4pi) M/(d^3)

⇒ (4pi xx 10^-7)/(4pi) xx (0.72sqrt(2))/d^3 = 18 xx 10^-6

⇒ d^3 = (0.72 xx 1.414 xx 10^-7)/(18 xx 10^-6)

⇒ d^3 = 0.005656

⇒ d = root(3)(0.005656)

⇒ d ≈ 0.2  "m" = 20  "cm"

Concept: Torque on a Magnetic Dipole (Bar Magnet) in a Uniform Magnetic Field
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#### APPEARS IN

HC Verma Class 11, Class 12 Concepts of Physics Vol. 2
Chapter 14 Permanent Magnets
Q 10 | Page 277