The magnetic field of the earth can be modelled by that of a point dipole placed at the centre of the earth. The dipole axis makes an angle of 11.3o with the axis of the earth. At Mumbai, declination is nearly zero. Then, a) the declination varies between 11.3o W to 11.3o E b) the least declination is 0o c) the plane defined by dipole axis and the earth axis passes through Greenwich d) declination average over the earth must be always negative
Correct option is A) Since the axis of the magnetic dipole placed at the centre of earth makes an angle of 11.3o with the axis of earth, the two possibilities arises as shown in given figure. Hence, the declination varies between 11.3oW to 11.3oE.
