Discuss Earth's magnetic field in detail.

Explanation

(i) Gover suggested that the Earth.s magnetic field is due to hot rays coming out from the Sun
(ii) These rays will heat up the air near equatorial region.
(iii) Once air becomes hotter, it rises above and will move towards northern and southern hemispheres and get electrified.
(iv) This may be responsible to magnetize the ferromagnetic materials near the Earth.s surface.
(v) Till date, so many theories have been proposed.
(vi) But none of the theory completely explains the cause for the Earth.s magnetism. The north pole of magnetic compass needle is attracted towards the magnetic south pole of the Earth which is near the geographic north pole.
(vii) Similarly, the south pole of magnetic compass needle is attracted towards the geographic north pole of the Earth which • is near magnetic north-pole.
(viii) The branch of physics which deals with the Earth.s magnetic field is called Geomagnetism or Terrestrial magnetism.
(ix) There are three quantities required to specify the magnetic field of the Earth on its surface, which are often called as the elements of the Earth.s magnetic field. They are
(a) magnetic declination (D)
(b) magnetic dip or inclination (1)
(c) the horizontal component of the Earth.s magnetic field (`B_H`)
The angle subtended by the Earth.s total magnetic field B with the horizontal direction in the magnetic meridian is called dip or magnetic inclination (I).
The component of Earth.s magnetic field along the horizontal direction in the magnetic meridian is called horizontal component of Earth.s magnetic field, denoted by `B_H`.