The earth’s magnetic field has both vertical and horizontal components

# Objective

To show that the earth's magnetic field has both vertical and horizontal components.

# Theory

The Earth's magnetic field is a complex phenomenon that arises from the movement of molten iron within its outer core. This movement generates electric currents, which in turn produce the Earth's magnetic field. The magnetic field consists of vertical and horizontal components, and these components can be explained by the theory of geomagnetism.

The theory of geomagnetism suggests that the Earth's magnetic field is primarily generated by a process called the dynamo effect. This effect relies on the convective motion of molten iron in the outer core, which is driven by the heat released from the solid inner core and the cooling of the outer core. The convective motion, combined with the Earth's rotation, creates a powerful geo-dynamo that generates the magnetic field.

## Magnetic Dip

Magnetic dip or inclination refers to the angle at which the magnetic field lines intersect the Earth's surface. The inclination varies with latitude, meaning that at various locations on Earth, the magnetic field lines will intersect the surface at different angles. Near the magnetic poles, the field lines are vertical, while at the magnetic equator, they are nearly horizontal.

The total magnetic field can be resolved into a horizontal component and a vertical component.

The vertical component of Earth's magnetic field can be found by the following equation.

Bv= B Sin(I)

The horizontal component of Earth's magnetic field can be found by following equation.

BH= B Cos(I)

B=Resultant magnetic field of Earth.

I =Angle of dip or angle of inclination.

Bv =Vertical component of Earth's magnetic field.

BH= Horizontal component of Earth's magnetic field.

## Magnetic Declination

Magnetic declination is the angle between the direction of true north (geographic north) and magnetic north. The decline also varies with location on Earth. In some areas, magnetic north aligns closely with true north, resulting in a small decline, while in other areas, the declination can be significant.

## Magnetic Field

Components of the Earth's magnetic field can be explained by the complex geometry of the magnetic field lines generated by the dynamo effect. The convective motion in the outer core gives rise to a dipolar magnetic field, meaning that the field lines resemble those of a bar magnet. This dipolar field contributes to the vertical component of the magnetic field.

However, other factors, such as the interaction of the Earth's magnetic field with external sources, such as the solar wind and the magnetospheric currents, can also influence the magnetic field's horizontal components. These interactions can cause the magnetic field lines to be distorted or deviated, leading to variations in the horizontal component of the field.

## Conclusion

In summary, the presence of both vertical and horizontal components in the Earth's magnetic field can be attributed to the dynamo effect caused by the molten iron's convective motion in the outer core, as well as external influences from the solar wind and magnetospheric currents. The intricate interaction of these factors gives rise to the observed variations in the Earth's magnetic field.

# Learning Outcomes

• Students can understand the magnetic fields.
• Students can understand the magnetic dips.
• Students can understand the magnetic declination.