The magnetic field of Earth can be modelled by that of a point dipole placed at the center of the Earth. The dipole axis makes an angle of with the axis of Earth. At Mumbai, declination is nearly zero.
Then,
A. the declination varies between W to E.
B. the least declination is°.
C. the plane defined by dipole axis and Earth axis passes through Greenwich.
D. declination averaged over Earth must always be negative.
The answer is the option (a) Earth’s magnetic field is similar to a magnetic dipole and we can simulate the nature of Earth’s magnetic field by assuming a dipole at the center of Earth. The axis of the dipole is at an angle of with respect to the axis of rotation.