Question

At the magnetic poles, earth’s total magnetic field is

(1) Perpendicular to surface of the earth

(2) Parallel to the surface of the earth

(3) zero

(4) will be at a dip of 60°

Answer 1

(1) Perpendicular to surface of the earth

Denoting by B, B_H and B_V , the total feild of earth, horizontal component of earth’s field and vertical component of earth’s field, we have

B_V = Bsin δ

where δ is the angle of dip.

At magnetic poles δ = 90° and hence B_H = 0

At the poles, the earth’s totoal field is, therefore, the same as its vertical component. It is, therefore, perpendicular to the surface of earth at the poles.