We all know that the Earth has its own magnetic field. And it is due to its composition and moreover due to its core. Our Earth’s core is composed of enormously heated metals in molten state under extreme high pressure. If you are an electrical guy, you must have read this before also that application of heat, friction, pressure etc are a mean of producing a potential (voltage). As these molten metals are exposed to heat, fiction as well as pressure, a potential (voltage) is developed in it. Thus, we can say that these molten metals are in continuous electrical contact and so, there is always a current flowing among themselves. This flow of current generates a magnetic field. We can split the Earth’s field into two magnetic components:
- Horizontal magnetic component of the Earth (H) – strongest at equator
- Vertical magnetic component of the Earth (Z) – strongest at magnetic poles.
The Horizontal magnetic component of the Earth (H) is at its peak at the Earth’s magnetic equator.
The Vertical magnetic component of the Earth (Z) is at its peak at Earth’s magnetic poles.
It should be kept in mind that the location of Earth’s magnetic poles differs from the Earth’s geographic pole. In actual, the Earth’s magnetic south pole is close to Earth’s geographic North pole. Similarly, the Earth’s magnetic north pole is close to Earth’s geographic South pole.
I hope you understood it. So, lets ask you a question then. If it is so, then why our magnetic compass shows the actual geographic north pole? It should show magnetic north pole, which is our geographic south pole.
The answer is very simple. When we seek direction from magnetic compass, its north pole always aligns with the magnetic south of the Earth, which is Earth’s geographic north pole. Thus, we should keep it in mind that the direction which a magnetic compass shows is only a geographic direction instead of the magnetic direction.
The difference between the magnetic and geographic poles of the Earth is also known as Magnetic deviation.
The strength of the Earth’s magnetic field at its surface is nearly 0.5 gauss. It reduces gradually when we moves towards the Earth’s north hemisphere.
The Earth’s magnetic field can be commonly referred to a dynamo effect of the circulating electric current. However, it should be noted that it is uneven at different locations. It has been observed and confirmed in a scientific review that the rock samples of various Earth years at the same places have different values of permanent magnetism. You will be surprised to know that reports of 172 magnetic field reversals has been confirmed within the last 71 M years.