The magnetic moment of the assumed dipole at the earth's centre is `8.0 xx 10^22 A m^2`. Calculate the magnetic field `B` at the geomagnetic poles of the earth. Radius of the earth is `6400 km`.

Explanation

To solve the problem of calculating the magnetic field \( B \) at the geomagnetic poles of the Earth, we can follow these steps:

### Step 1: Understand the formula for the magnetic field at the poles of a dipole
The magnetic field \( B \) at the axial point of a magnetic dipole is given by the formula:
\[ B = \frac{\mu_0}{4\pi} \cdot \frac{2m}{d^3} \]
where:
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