The magnetic field of Earth can be modelled by that of a point dipole placed at the centre of the Earth. The dipole axis makes an angle of `11*3^@` with the axis of Earth. At Mumbai, declination is nearly zero. Then,

Options

A. the declination varies between `11.3^@` W to `11.3^@` E
B. the least declination is `0^@`
C. the plane defined by dipole axis and Earth axis passes through Greenwich.
D. declination averaged over Earth must be always negative.

Answer

A

Explanation

Two cases are possible for the declination of `11.3^@` on both sides of Mumbai. Zero declination means Mumbai lies on common plane containing magnetic and geographic poles of same side.

So, we can say that declination varies between `11.3^@` W to `11.3^@` E