Magnetic Field Earth Magnetism - Definition, Cause, Theory, FAQs

Edited By Vishal kumar | Updated on Sep 24, 2024 05:50 PM IST

A compass is helpful to find the directions and the needle inside the compass always points in the north direction. The compass could be traditionally used as a mechanical compass or inbuilt smartphone component or it could be a refrigerator magnet, all these points towards the north direction. Do you know why it is so? What's the reason behind it? It is because of Earth’ magnetism. Let us discuss the earth's magnetic field and earth magnetism and define earth's magnetic inclination and declination angle and the horizontal component of the earth's magnetic field, transverse magnetic field and the earth magnetic field direction and the earth's magnetic poles and so on.

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Magnetic Field Earth Magnetism - Definition, Cause, Theory, FAQs

The magnetic field is found to be the component that acts similar to a protective layer around the Earth. This magnetic field of the earth does not allow the unwanted charged particles of the sun by repelling and trapping the particles and unwanted wave signals. The magnetic field of the earth is not only present inside the earth, it also extends for some millions of kilometres outside the earth diameter and the whole earth acts like a bar magnet. The magnetic field has a very weak force compared with other fundamental forces.

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Dynamo effect - the cause of Earth magnetism:

The theory which gives a good explanation of the cause of the earth's magnetic system is known as the Dynamo effect. The Dynamo effect explains that the Earth maintains the magnetic field lines on its own due to the metallic fluids which are present in both the outer and inner core of the earth. Molten iron is present in the outer core and the solidified elements present in the inner core plays an important role in the cause of Earth. Magnetism.

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Some convection currents which are formed by the molten iron and the nickel of the earth's core produce the Earth’s magnetic field. These convection currents carry few streams of charged particles which causes the magnetic field. The deflection of the magnetic field is caused due to the solar wind caused by the Sun and prevents the entry of these solar winds into our atmosphere. If the magnetic field is removed from the Earth, then these solar winds could destroy the whole earth and life would not exist on Earth. The planet Mars lacks these magnetic fields and this is the reason life does not exist on the planet mars.

NCERT Physics Notes:

this image portrays the earth's magnetic field and magnetic poles are well depicted

About magnetic poles:

The poles of these magnetic fields are inclined by 10 degrees to the rotational axis of the Earth i.e. instead of aligning in the actual geographic north - south direction, the earth magnetic pole of the south is present near Canada and the earth magnetic pole of the north is present in Antarctica.

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Three components of the magnetic field of Earth:

The magnitude and direction of the earth's magnetism are calculated by using the three major components. The three components are listed below

Magnetic declination
The angle of dip (which is known as magnetic inclination)
Earth's magnetic field’s horizontal component

Let us discuss the components in detail.

Magnetic declination:

The concept of magnetic declination gives us the angle that lies between the magnetic north and true north. The fact is, this true north does not have a fixed or constant position on the horizontal plane. It varies according to the surface of the earth and time.

The angle of dip:

The angle of dip is also called magnetic inclination. This magnetic inclination is an angle that is caused by the plane horizontal to the earth’s surface. This magnetic inclination angle is found to be 0 degrees at the magnetic equator of the earth and the magnetic inclination angle at the magnetic poles is found to be 90 degrees.

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Earth's magnetic field’s horizontal component:

The intensity of the magnetic field of earth breaks into two different components, i.e. horizontal component and a vertical component.

tanδ= B_(v)/B(_h)

sinδ= B_(v)/B

cosδ= B_(h)/B

sin²δ+cos²δ =B²_(v)/B²+ B_(h)²/B²

$B=\sqrt{B_{(h)}^2+B_{(v)}^2}$

Where B represents the total magnetic field intensity or strength and is a vector component.

B can be also written as follows

$B=\sqrt{X^2+ Y^2+Z^2}$

Where, X, Y, Z represents the components of the magnetic field along the geographic north,

geographic east and vertically downward direction respectively.

X and Y can be found out by using the below formula

X=Hcosα and Y=Hsinα

Where H represents the component of the magnetic field that is parallel to the surface of the earth and this H is equal to √(X²+Y²)

? represents the magnetic declination angle ( which is known as the angle between true and magnetic north) and this ? is equal to tan^-1(XY).

While the θ represents the magnetic inclination angle ( which is known as the angle of the horizontal component of the magnetic field) and this θ is equal to tan^-1(ZH)

In this article, we discussed the concepts of earth magnetic field lines, magnetic elements, earth magnetic field strength, elements of earth magnetic field, theory of magnetism, terrestrial magnetism, origin of magnetism, cause of earth magnetism, geomagnetic field and earths magnetism. Now let us answer some frequently asked questions from the topic of Earth’s Magnetism

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Frequently Asked Questions (FAQs)

1. What is the horizontal component of the earth magnetic field value?

The value of the component of the earth’s magnetic field which is horizontal is found to be zero.

2. What is the earth magnetic field value (in terms of nT)?

The earth magnetic field value lies around 25,000 nT to 65,000 nT.

3. What is known as the earth's magnetosphere?

The system of magnetic fields that are covered and surrounded by the atmosphere of the Earth is known as the earth's magnetosphere.

4. Define magnetic compass

Magnetic compass direction-finding device in which the needle always points to the north direction and helps us to find the direction on Earth.

5. Why does the earth have a magnetic field?

The deflection of the magnetic field is caused due to the solar wind caused by the Sun and prevents the entry of these solar winds into our atmosphere. If the magnetic field is removed from the Earth, then these solar winds could destroy the whole earth and life would not exist on Earth. This is why the earth requires a magnetic field.

6. What is the dynamo effect?

The Dynamo effect tells us that the Earth includes the magnetic field lines on its own due to the metallic fluids which are present in both the outer and inner core of the earth. Molten iron is present in the outer core and the solidified magnetic elements of earth present in the inner core plays an important role in the cause of Earth

7. Define the horizontal components of earth magnetic field and write the horizontal component of the earth's magnetic field formula?