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The magnetic field of Earth can be model...

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,

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 the earth axis passes through Greenwhich

D

declination averaged over the earth must be always negative

Text Solution

Verified by Experts

The correct Answer is:
A
For the earth's magnetism, the magnetic field line of the earth resemble that of a hypothetical magnetic dipole located at the centre of the earth. The axis of the dipole does not coincide with the axis of ratoationof the earth but is presntly titled with the axis of rotation of the earth but is presently titled by approximately `11.3^(@)` with respect to the later. This results into two situations as given in the figure ahead.

Hence, the declination varies between `11.3^(@) W "to" 11.3^(@)E`
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