What is the cause of Earth’s magnetism?

Earth’s Magnetism

Earth has been considered or imagined by scientists as a big magnetic dipole. Still, the position of the Earth’s magnetic poles is not well explained in the earth.

The south pole of the imaginary magnet inside the earth is found near the geographic north pole and the north pole of the earth’s magnet is found near the geographic south pole.

The line joining these magnetic poles is called the magnetic axis. The magnetic axis crosses the geographic north pole at a point called the north geomagnetic pole or northern magnetic pole.

It crosses the geographic south pole at a point called the south geomagnetic pole or southern magnetic pole. The magnetic axis and the geographic axis (axis of rotation) do not coincide with each other.

The magnetic axis of the earth is tilted at an angle of approximately 10° to 15° with the geographical axis.

Magnetism of earth
Earth Magnetism

Even today the exact reason for earth magnetism is not known.

Some of the causes of earth magnetism are:

  • Masses of the magnetic substances in the earth.
  • Radiations from the Sun.
  • Influence of the moon. 

Nevertheless, it is also thought that the Earth’s magnetic field is due to the molten charged metallic liquid inside the earth with a core of radius of approximately 3500km compared to the Earth’s radius of 6400 km.

Earth’s Magnetic Field

The north pole of a magnetic needle generally points towards the geographic north (NG). Thus, it is relevant to conclude that the magnetic north pole of the needle is attracted by the magnetic south pole of the Earth (Sm), which is located at the geographic north NG.

Also, the magnetic south pole of the needle is dragged by the magnetic north pole of the earth (Nm), which is positioned at the geographic south SG. The magnitude of the magnetic field intensity at the Earth’s surface ranges from 25 to 65 microtesla.

Earth magnet is almost 20 times powerful than the refrigerator magnet.

* * All the Notes in this blog, are referred from Tamil Nadu State Board Books and Samacheer Kalvi Books. Kindly check with the original Tamil Nadu state board books and Ncert Books.
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