Question

The magnetic field of earth at the equator is approximately $4\times {10}^{-5}T$. The radius of earth is $6.4\times {10}^{6}m$. Then the dipole moment of the earth will be near the order of

• A. ${10}^{23}A{m}^2$
• B. ${10}^{20}A{m}^2$
• C. ${10}^{16}A{m}^2$
• D. ${10}^{10}A{m}^2$

Answer 1

Answer: (A)

${10}^{23}A{m}^2$

$B=\frac{{\mu }_{o}m}{4\pi d^3}=\frac{4\times {10}^{-7}}{4\pi (6.4\times {10}^6{)}^3}=\approx {10}^{23}A{m}^2$