Students studying the NCERT solutions for class 8 Science will find this topic interesting. This article will talk about magnetic force, its types, applications and properties. Moreover, we shall show students how Magnetic Force helps sustain life on Earth. Hence, it is a very important force to learn about.
The Link between Earth’s Water and Magnetic Force
Fact- There is no evidence of life on Venus or Mars. However, Earth is hospitable and sustains life. Moreover, it’s been found that both these planets are not surrounded by magnetic fields whereas Earth is.
Moreover, more than 70% of Earth’s surface is covered with water. In fact, plants and animals cannot live without water.
Isn’t that an interesting observation?
What do you infer from these facts?
Therefore, scientists believe that it is the Earth’s magnetic field that allows for the presence of water on Earth. Hence, life is possible on Earth due to the presence of water and Earth’s magnetic force.
Let’s understand a little more about what is magnetic force and how the Earth generates a magnetic field.
What is Magnetic Force?
Magnets- those small little round or square shaped one we all have used to pull coins or iron nails to. Moreover, many of us also buy fridge magnets to decorate their homes or as souvenirs.
Similarly, most of us are familiar with a compass and know that it indicates the North direction in a static position.
And that’s because it aligns with the Earth’s magnetic field.
As a matter of fact, the Earth is also considered a giant magnet.
But what exactly is this force that the magnets exert. Well, we term it as magnetic force.
The force exerted when an object is pulled towards or pushed away from a magnetic source is known as magnetic force.
How is magnetic force created?
Mostly, by the movement of electrically charged particles.
Presence of a Magnetic Field on Earth
Now, this is a very interesting topic.
Surely, we all wonder whether the Earth is surrounded by a magnetic field. Additionally, how does it function?
Definitely, the Earth exerts a magnetic force and field
Let us understand how the Earth exerts a magnetic pull. And for that we have to understand that there is a correlation between electric fields and magnetic fields.
Generally, moving electric currents create magnetic fields around them.
As a matter of fact, the Earth’s core generates electric current.
Did you know about that?
Hence as explained above when the electric current generated in the Earth’s core starts circulating, it gives rise to magnetic fields.
Moreover, this magnetic field is a self- sustaining one. This means it happens in a loop and is expected to do so for many millions of years.
Generally, scientists compare the Earth’s magnetic field as the force generated by a dynamo.
Read on to understand the concept of a dynamo and geodynamo.
Easy to understand Explanation about a Dynamo
So, what exactly is a dynamo and how does it compare to the Earth’s magnetic field.
Let’s quickly understand.
Basically, and to put it across simply a dynamo is a machine that produces energy.
Dynamo implies power, force, and energy.
In common use, it means a machine that converts energy from one form into another. Primarily, it converts mechanical energy into electrical energy.
Hence, it creates a direct current or DC.
And how does this happen?
When coils of copper wire rotate in the presence of a magnet, which exerts a magnetic field, can induce voltage.
Basically, this is the basic principle on which a dynamo works.
A dynamo is fitted with a magnet that exerts a magnetic field. Now, when the coils within it move, in the filed it generates electricity.
For instance, an easy-to-understand example is the bicycle dynamo.
The bicycle dynamo a common and well-known example.
The bicycle dynamo is fitted onto a bicycle. Its primary function is to provide power for the bicycle lights.
Basically, the dynamo is a device that generates electricity to power up the bicycle lights.
So, how does the bicycle dynamo work?
Basically, the dynamo is a machine fitted with a magnet.
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Furthermore, this magnet is surrounded by coils of wire. Now, when the magnet undergoes rotation it lets off a dynamic or changing magnetic field. This in turn produces electricity in the wire coils. Moreover, the dynamo is fitted in such a way that its wheel touches the bicycle tyre. Hence, when the cycle moves, the wheel moves to turn the magnet within the coil. Therefore, producing electricity as explained above. The electricity produced is enough to power the bicycle lights.
Earth’s GeoDynamo Effect
The Earth’s Dynamo theory was explained by an American physicist- Walter M. Elsasser and a British geophysicist Edward Bullard. It stands till date to the most popular one.
The Dynamo Theory for celestial bodies implies a method by which the celestial body generates and sustains a magnetic field over millions of years.
The Earth is made up of many layers. Moreover, all layers’ are made up of different constituent materials. All of these materials exhibit different chemical compositions. Consequentially, they exhibit different physical properties as well. All of this combine and create a state of convective turbulence on the Earth’s outer core.
Additionally, the Earth’s rotation also exerts some effects on this turbulence. When these two effects combine, the kinetic energy gets converted into electrical and magnetic energy.
Hence, as the process continues in a loop, we say that the magnetic fields emanating from the Earth are self-sustaining.
To summarise, the Earth’s outer core is the location of origin for the Earth’s magnetic fields
This happens as metals are in a fluid state in the earth’s outer core. This happens due to variances in pressure between the inner and outer cores of the Earth.
Hence, currents are created in molten iron, which upon movement gives rise to electrical energy. Furthermore, this goes on to produce magnetic fields. This constant cycle of the Earth’s core emanating magnetic fields is known as the geodynamo effect.
Magnetic Force has Everyday Applications
We use magnetic force in our day-to-day life as well. From electronic gadgets to technological gadgets. Refrigerators, MRI scans, compass, speakers, computers, cars and even microwave ovens are just a few examples of how we apply magnetic force. The use of magnetic force is helpful and solves many of our day-to-day problems.
For example, take the compass. We all know that it is a very handy device. It helps us track the direction. It is a handy tool for people who hike, travel and even for architects. The compass needle always has a reference point in the North direction. And from there, you can choose your desired direction.
Now, do you know why it points to the North? That’s because it aligns itself to the Earth’s magnetic field.
Now isn’t that an interesting fact?
To conclude, the magnetic force is a powerful and vital force. We have learnt about its use in sustaining life on earth as well as some common day-to-day examples. We hope that students who search for what is a magnetic force in class 8 have learnt some interesting information about magnetic force.