The magnetic field of a planet at any location is approximately 0.5 G. Estimate its dipole moment if its position from the centre is $25.6 \times 10^6 M$. Assume the planet to be of spherical shape:

$8.39 \times 10^{24} Am^2$

The correct answer is Option (3) → $8.39 \times 10^{24} Am^2$

The equitorial magnetic field is -

$B=\frac{μ_0}{4π}\frac{M}{r^3}$

where,

B, Magnetic field = $0.5G=0.5×10^{-4}T$

$r$, radius from center of planet = $25.6×10^6m$

$M=\frac{Br^3}{\frac{μ_0}{4π}}=\frac{(0.5×10^{-4})×(25.6×10^6)^3}{2×10^{-7}}$

$≃8.39×10^{24}Am^2$