The last time we saw how electricity permeates our lives, how a simple experiment with a balloon helps us understand the catastrophic lightning, so this time we will discover how and why magnetism is deeply connected to electricity, how these amazing forces of nature create The Northern and The Southern lights(Auroras).



EARTH IS A MAGNET.

One of the most remarkable and astounding discoveries, which has been used by explorers from many years , is that if you touch a needle to magnetite(Fe3O4, a highly magnetic substance), it induces magnetism into the needle, and no matter in which direction you turn, the needle keeps pointing to the North and South, always. It was believed, that the needle points to the Pole star, Polaris or there were Magnetic Islands in the North and the South. William Gilbert , the physician of Queen Elizabeth I showed that the Earth itself is a magnet and the needle points toward it's North and the South pole.



THE ELEGANT AURORA

Aurora australis from the International Space Station,2017.





An aurora over Estonia, 18 March 2015.









Here is what happens, the Sun sometimes emits a stream of charged particles, mostly protons and electrons, and some of this plasma(Ionized gas) travels towards the Earth, but because of the Earth's magnetic field, all of this plasma is pushed towards the Northern and the Southern region, where the magnetic field of the Earth is the strongest. These charged particles when enter the atmosphere, they interact with the different gases or elements in the atmosphere.

Aurora Borealis seen from the Arctic circle, photographed by Miguel Claro.





The interaction with Oxygen produces green and red lights, while that with Nitrogen produces blue and red lights . And the end result of all of this, is the beautiful and majestic aurora. Although these are very pretty to look at, a lot of solar wind can cause serious problems on Earth in communication and Radio signals, it can be really problematic!



WHY DOES THE EARTH HAVE A MAGNETIC FIELD?

Well the answer to this question is a little complicated, but here is an easy way to understand it. Danish physicist Hans Orsted , while performing an experiment in his class, found that as he started a flow of current in wire attached to a battery, the compass needle nearby deflected , in a direction perpendicular to the flow of current, away from the North and the South pole. When he switched off the current, the needle would come back to its original position. This is the only time, in course of physics that a discovery was made in front of an entire class, how lucky those students were right?



The north of a magnet points to the South pole of the Earth, and vice versa.



What Orsted found out was that moving electric charges produced a magnetic field, and this is what deflected the compass needle. A simple yet truly astonishing result, which gave birth to the research of 19th century physics on Electromagnetism. But the truly amazing wonder of these two is still yet to come...We will come back to this question soon.



HOW MICHAEL FARDY LIGHTS UP OUR WORLD.



Michael Faraday , also known as The Electric Boy, is responsible for the electricity that lights up you house, the air conditioner that makes you feel cool, the television that entertains you, or how you charge your phone, or how you use a microwave oven and on and on and on...He found out, the when you moved a magnet in a coil, electric current is produced in it. The entire world economy in the 21st century is based on this simple experiment and result by Faraday, exciting isn't it? Every generator uses this idea, the only difference is we move coil in a magnetic field to produce electricity, the magnet remains stationary. In a way Faraday turned Orsted's idea upside down, and showed us how deeply electricity and magnetism are related. Today, we call this Faraday's Law.



FUN FACT : The legend is that a politician once asked Farady if his discovery had any practical use, he responded "Sir , I do not know what it is good for , However I am quite certain; some day you will tax it."



So you may think the Earth gets its magnetic field because of it's molten magnetic core, but that is not truly the reason. In fact Physicists are still working on a complete mathematical model to understand Earth's magnetic field. It has to do with the electric current flowing through the Earth and the fact that the Earth is rotating, which we call The Dynamo Effect.



MARS AND IT'S THIN ATMOSPHERE.

Mars is a very good reminder to us on why the magnetic field is so important. The thin atmosphere on Mars is due to it's weak magnetic field, because all the solar wind blew away the Martian atmosphere, which accounts for the lack of water on Mars and making it hard for life to exist .





This is why life itself, on Earth owes its existence to its magnetic field, that surrounds us and permeates us all the time,LET THAT SINK IN.





"But still try , for who knows what is possible!"

-Michael Faraday.





Article by : Shanawaz Shaikh (F.Y.BSc)