Discuss Earth's magnetic field in detail.

Explanation

Gover suggested that the earth.s magnetic field is due to hot rays coming out from the sun. these rays will heat up the air near equatorial region. Once air becomes hotter, it rises above and will move towards northern and southern hemispheres nd get electrified this may be responsible to magnetize the ferromagnetic materials near the earth.s surface.
the north pole of magnetic compass needle is attracted towards the magentic south pole of the earth which is near the geographic north pole . similarly, the south pole of magnetic compass needle is attracted towards the geographic north pole of the earth which is near magnetic north pole. there are three quantities required to specify the magentic field of the earth on tis surface , which are often called as the elements of the Earths magnetic field. they are :
(a) Magnetic declination (D) :
The angle between magnetic meridian at a point and geographical meridian is called the declination or magnetic declination (D ) .
(b) Magnetic dip or inclination (I) :
The angle subtended by the earth.s total magnetic field `vec(B)` with the horizontal directon in the magnetic meridian is called dip or magnetic inlination (I) at that point.
(c ) The horizontal component of the earth.s magnetic field `(B_(H))`:
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)`.
Let `B_(E )` be the earth.s magnetic field at a point P on the surface of the Earth . `B_(E )` can be resolved into two perpendicular components .
Horizontal component `B_(H) = B_(E) ` cos I `" "`....(1)
Vertical component `B_(V) = B_(E)` sin I `" "`....(2)
Dividing the equation, we get tan I = `(B_(V))/(B_(H)) " "`.....(3)
(i) At magnetic equator The earth.s magnetic field is parallel to the surface of the earth (i.e., horizontal ) which implies that the needle of magnetic compass rests horizontally at an angle of dip , I = `0^(@)` .
`B_(H) = B_(E)" " B_(V) = 0 `
This implies that the horizontal component is maximum at equator and vertical component is zero at equator .
(ii) At magnetic poles. The Earth. s magnetic field is perpendicular to the surface of the earth (i.e., vertical ) which implies that the needle of magnetic compass rests vertically at an angle of dip , I = `90^(@)` .
`B_(H) = 0" " B_(V) = B_(E ) `
This implies that the vertical component is maximum at poles and horizontal component is zero at poles.