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The earth magnetic field at the equator ...

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

Text Solution

Verified by Experts

From Eq (5.7), the equatorial magnetic field is `B_(E)=(mu_(0)m)/(4pi r^(3))`
We are given that `B_(E)-0.4G=4 xx 106(-5)T.` For r we take the radius of the earth `6.4 xx 10^(6) m`. Hence `m=(4 xx 10^(-5) xx (6.4 xx 10^(6))^(3))/(mu_(0)//4pi)=4 xx 10^(2) xx (6.4 xx 10^(6))^(3) (mu_(0)//4pi=10^(-7))`
`=1.05 xx 10^(23) Am^(2)`
This is close to the value of `8 xx 10^(22) A m^(2)` quoted in geomegnetic texts.
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