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प्रश्न
The magnetic moment of the assumed dipole at the earth's centre is 8.0 × 1022 A m2. Calculate the magnetic field B at the geomagnetic poles of the earth. Radius of the earth is 6400 km.
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उत्तर
Given :
Magnetic moment of dipole at Earth's centre, M = `8.0 xx 10^22 "Am"^2`
Radius of Earth, `d = 6400 "km"`
The geomagnetic pole is at the end of the position (axial) of Earth.
Thus, the magnetic field at the axial point of the dipole (B) is given by
`B = (u_0)/(4pi) (2M)/d^3`
⇒ `B = (10^-7 xx 2 xx 8 xx 10^22)/((64)^3 xx 10^15)`
⇒ `B = 6 xx 10^-5 "T" = 60 "uT"`
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