Question

Consider a perfect Geocentric Axial Dipole model for the geomagnetic field. At a latitude of 30°N, the inclination of a freely suspended magnetic needle, in degree, is ............ (Round off to the nearest integer)

Hint:

In the Geocentric Axial Dipole model, the inclination of the magnetic field is directly related to the latitude. At the equator, the inclination is 0°, and at the poles, the inclination is 90°.

Answer 1

Correct Answer: 60

Step 1:
For the Geocentric Axial Dipole model, the formula for the magnetic inclination (\(I\)) at a latitude \(\phi\) is:
\[ I = \tan^{-1}( \tan(\phi) ) \]

Step 2: Given latitude \(\phi = 30^\circ\), we can substitute:
\[ I = \tan^{-1}( \tan(30^\circ) ) = 60^\circ \]
Thus, the inclination at 30°N is \(60^\circ\).
\[ \boxed{60^\circ} \]