An introduction to electromagnetism and two important aspects

The use of electromagnetism can be noticed all around us. We cannot imagine a world where there are no electric lights, no telephones, no personal computers, and no trains. All of these are happening because of the electromagnetic effects.

History of electromagnetism

 Scientist, Oersted in his experiments, demonstrated that electric currents could produce a magnetic field, and Faraday experimentally illustrated the reverse process. The conclusion of these experiments was that electric fields could be generated by a varying magnetic field, and magnetic fields can be generated by an electric field or simply electric currents. James Clerk Maxwell also has contributed immensely to the relation between electric and magnetic fields.

Oersted , Image Credit – Christoffer Wilhelm Eckersberg artist QS:P170,Q363823, Ørsted, marked as public domain, more details on Wikimedia Commons
James Clerk Maxwell , Image Credit – George J. Stodart creator QS:P170,Q19832615, James Clerk Maxwell, marked as public domain, more details on Wikimedia Commons

Later, Einstein, also through his special theory of relativity, stated that they are interrelated and can be treated as a single phenomenon. The interaction between electricity and magnetism, which we study in this branch is known as Electromagnetism.

What is Electromagnetism? 

When current flows through a conductor (e.g., coil, wire), a magnetic field is induced. This process, in general, is known as electromagnetism. The directions of the induced magnetic field line is determinable by the right-hand screw rule.

In this, we imagine that we are holding the wire through which current flows such that our thumb points towards the direction of current and the way in which the magnetic field lines curls around the wire is similar to the curling of the other fingers. This way, we can find the direction of the magnetic field of a wire.

right hand thumb rule
right-hand thumb rule
magnetic field around a current carrying wire
magnetic field lines direction around a current carrying wire

Now once the direction and orientation of the magnetic field are determined, the next question arises to be what its magnitude is? The magnetic field surrounding a current-carrying wire is relatively weak for amounts of current generally used in practical applications just sufficient enough to deflect a small compass needle and more.

For creation of strong magnetic fields and as a result greater amount of flux with the equal amount electric current, wires can be wrapped to a coil in which the individual circulating magnetic fields around the wires will subsequently sum up.

Magnetic field lines due to a current carrying coil
Magnetic field lines due to a current carrying coil, Image Credit – Geek3VFPt Solenoid correct2CC BY-SA 3.0

A brief explanation of electric current and magnetism as two essential aspects of Electromagnetism

An essential part of electromagnetism is the concept of electricity or electric current, which is, in turn, related to the behaviour of charges inside matter, including their distribution and motion. Different materials are classified as conductors or insulators on the basis of the motion of charges inside them. Electric current can be simply said to be the measure of the flow of charges.

Another essential part of electromagnetism is magnetism. The science of magnetism was born when different observations were made on ores that could attract small pieces of iron and pointed in a particular direction when kept on the floating cork. Later it was deducted that this phenomenon was the result of different spin magnetic moments of elementary particles.

What are Electromagnetic Waves?

The mathematical electromagnetic equations given by Maxwell show that electric field and magnetic field travel all-together through the space as wave. This is possible as a changing magnetic field will induce a changing electric field and vice-versa, and these changing fields travel through space mutually perpendicular to each other, even in the absence of any medium. These kinds of waves were then termed as Electromagnetic waves.

Electromagnetic Waves
Electromagnetic Waves
Image Credit: And1muEM-WaveCC BY-SA 4.0

What is electromagnetic induction?

For understanding electromagnetic induction first, we need to know about magnetic flux. Like electric flux, magnetic flux is proportional to the number of magnetic field lines passing through a surface. The relative motion of any magnetic field and a conductor results in a change of magnetic flux through the conductor, which results in the production of an induced electromotive force (emf) or voltage. This phenomenon is known as electromagnetic induction. You will learn more about electromagnetic induction in the upcoming section.

magnetic field induction using electric field , Image Credit – Simple_electromagnet.gif: The original uploader was Berserkerus at Russian Wikipedia. derivative work: Chetvorno (talk) Alterations to source image: Rotated CCW 90° and lightened to bring out detail., Simple electromagnet2, marked as public domain, more details on Wikimedia Commons

What is the electromagnetic force?

The electric force acts for charged particles. But the magnetic force acts on moving charged particles. Hence the combination of electric and magnetic forces on a charged particle can be summed up as electromagnetic force.

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