# Earth - magnetic field of Earth

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## Earth -  magnetic field of Earth

Introduction:

The  magnetic field of Earth is generated in the outer core fluid by a self-exciting dynamo process. The currents which are flowing inside the slowly moving molten iron generates  the magnetic field . the magnetic field observable at the Earth's surface has sources in the earth's crust and in the ionosphere and the magnetosphere.

The geomagnetic field varies in a range of scales and the description of these variations is now available ,  low frequency to high frequency variations, in both the space and the time criteria . The final section of the variations describes how the Earth's magnetic field can be both a tool and a hazard to the modern world. First of all, however, methods of observing the  magnetic field are described.

Sir William Gilbert  , an English scientist and physician who is credited by many as the father of electricity and magnetism .He was the first person to suggest that earth itself is a huge magnet . When he observed that the magnetic  forces most often produced circular motions, he began  connecting the phenomenon of the magnetism  with the rotation of the earth .

### Earth -  magnetic field of Earth

#### His statement was based on the following evidence :-

1)   According to sir William gilbert , a magnet when suspended from a thread comes to rest along the N-S direction. This is as, if a huge fictitious magnet is buried along the diameter of the earth. The N-pole of this fictitious magnet must be towards Geographic south, so as to attract the South Pole of suspended magnet and vice versa.

2)  As far as second evidence is concerned, it states that when a soft iron core is buried under the earth in North south direction, it is founded that the iron core acquires the properties of the magnet after some time.

The above two evidences discussed showed that the earth behaves as a magnet.

 Earth
Note :

The branch of physics which deals with the study of earth's magnetism is called geomagnetism . The strength of earth's magnetic field is 1 gauss.

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#### Cause of earth's magnetic field :

The exact cause of earth's magnetic field has not been uncovered yet. However, it is believed that On Earth, flowing of the liquid metal in the outer core of the earth's surface generates the electric currents. The rotation of the Earth on its axis causes these electric currents to form a magnetic field which extends around the whole planet. However,  some important postulates in this respect are :

1) There is a metallic molten charged fluid inside the core of the earth . It is believed that the radius of this fluid is of about 3500km. Due to the motion of this fluid in the core of the earth, large circulating currents are produced. These currents magnetise the earth. In other words, we can say that these currents produce the effect of magnetism inside the earth.

2) In the outer layers of the earth's atmosphere, gases are in the ionised state. Due to the rotation of the earth, these ions also move and hence they constitute the current inside the earth. These currents can also be the reason for the magnetism of the earth.

3) We know that, every substance is made up of protons and electrons . when earth rotates, every substance on or inside the earth will also rotate. Hence, there is motion of protons and electrons inside the earth and due to this reason, currents are produced inside the earth. This can also be the reason for the magnetism of the earth.

#### Importance of earth's magnetism :

The magnetic field is extremely important to sustain  life on the Earth. Without the presence of magnetic field inside the earth , we would be exposed to higher amounts of radiation from the Sun and our atmosphere would be free to leak into the space.

The  magnetic field  of Earth has so much importance. For any planet in any star system, a magnetic field must be present for life to originate and its sustenance. Therefore, it is considered as an important field to search for life on other planets.

I would like to help you in understanding the above concept with the example of Mars . Mars doesn't have any kind of fluid flowing in it's core .It does not produce the same dynamo effect as is produced by the earth. This caused the planet deficient of magnetic field ,which in turn results in the  atmosphere of Mars to be stripped away by the Solar winds means making Mars uninhabitable.

Conclusion:

This article has discussed about the concept of earth's magnetic field . The article also provides you information related to the causes and important of earth's magnetic field. By the end of the topic, the concept of earth's magnetic field is clear.