The earth’s magnetic field at the equator is approximately 0.4 G. Estimate the earth’s dipole moment.

Explanation

`B_(E)=mu_(0)M/4pir^(3)`
We are given that `B_(E) ~ 0.4G =4xx10^(-5)T`.For r, we take the radius of the earth `6.4xx10^(6)`m.
Hence.`M=4xx10^(-5)xx(6.4xx10^(6))^(3)/mu_(0)//4pi=4xx10^(2)xx(6.4xx10^(6))^(3)`
`=1.05xx10^(23)Am^(2)`