Question

The earth's magnetic field lines resemble that of a dipole at the centre of the earth. If the magnetic moment of this dipole is close to 8 × 10²² Am², the value of earth's magnetic field near the equator is close to ______. (radius of the earth = 6.4 × 10⁶ m)

Options

• 0.6 Gauss

• 1.2 Gauss

• 1.8 Gauss

• 0.32 Gauss

Answer 1

The earth's magnetic field lines resemble that of a dipole at the centre of the earth. If the magnetic moment of this dipole is close to 8 × 10²² Am², the value of earth's magnetic field near the equator is close to 0.6 Gauss. (radius of the earth = 6.4 × 10⁶ m)

Explanation:

Given M = 8 × 10²² Am²

d = R_e = 6.4 × 10⁶ m

Earth's magnetic field, B = `mu_0/(4pi).(2"M")/"d"^3`

= `(4pixx10^-7)/(4pi)xx(2xx8xx10^22)/((6.4xx10^6)^3)` ≅ 0.6 Gauss