What are Electromagnets?, | What causes the Earth's Magnetic field?, |What is Aurora?

What are electromagnets?

In 1819,a Danish scientist Hans Oersted,While doing an experiment,observed that a magnetic needle lying on the side got deflected when he switched on the current.The needle went back to its original position when the current was switched off.Electrical current,thus,appeared to generate a magnetic field.This discovery by Oersted allowed us to make electromagnets.An electromagnet is an insulated wire wound around a piece of iron.The current flowing through the 'coil'generates a magnetic field that magnetizes the iron in the coil.The stronger the current, the stronger the electromagnet.

What causes the Earth's magnetic field?

In the Earth's core,a viscous mass containing iron moves around a solid iron core.According to scientists,this flow of iron acts like an electrical coil and is the cause of the Earth's magnetic field.Like any other magnet the Earth has a north pole and a south pole.These poles lie some thousands of kilometres away from the geographical poles.Not only sailors and pilots but also many migratory birds,dolphins,and salmons orient themselves to the magnetic field of the Earth.Small crystals of magnetite in their heads,acting like tiny compass needles,impart them a'magnetic sense'.

What is aurora?

Polar lights,or aurora,are bright bands of light that streak in the sky of the polar regions.The sun emits high-energy ion particles.These electrically charged particles,also known as solar wind,get deflected by the earth's magnetic field.As a result they are drawn magnetically down into the ionosphere above the Earth's surface at the poles.Their collision with the gas particles of the air causes the impressive display of colour in the northern sky.The magnetic field of the Earth protects us from the solar wind,which would otherwise destroy all life on the Earth.