# Earth magnetism

Today we are going to discuss about earth magnetism.

### 1. Geographic axis

This is a line which joins geographical north to geographical south of earth and passing through earth centre is called geographical axis.

### 2. Geographic equator

It is a greater circle which divides the earth into two equal halls and on surface of which geographic axis is perpendicular.

### 3. Geographic meridian

It's the greatest plane which divides the earth into two equal half and on which geographic axis is perpendicular is called geographic meridian.

### 4. Magnetic axis

This is the line which joins actual north and actual south of earth, passing through the center and along which the earth rotates is called magnetic axis.

### 5. Magnetic equator

It is the greatest circle which divides the earth into two equal halves and on which magnetic axis lie perpendicular is called magnetic equator.

### 6. Magnetic meridian

It is the greatest plane which divides the earth into two equal halves and on which magnetic axis is perpendicular is called magnetic meridian.

## Geographical view of earth

Now, let's discuss about geographical view of earth.

• Earth is spherical when seen from outside.

• Earth is planner in shape when seen from earth surface only.

## Magnetic elements of earth

Now, let's discuss about magnetic elements of earth.

#### What are magnetic elements of earth ?

Magnetic elements of earth are those variables or quantities with the help of which the total earth magnetism can be determined at any point on the earth surface are called magnetic elements of  earth.

### 1. Magnetic declination

Magnetic declination at any point on earth surface is defined as the angle between the magnetic meridian and geographic meridian at that plane.

### 2. Magnetic inclination

It's also called angle of dip.

Angle of dip at any plane of earth surface is defined as the angle at which earth total magnetic field make with the latitude at the place.

### magnetic field

It's the component of earth magnetic field along the horizontal direction [ latitude ].