G. Rajasekaran

We are able to talk with someone hundreds or thousands of kilometers away using a small hand-held gadget. Space scientists are able to control the spacecraft travelling millions of kilometers away, sitting here. Many such wonders! All these are possible only because of the electromagnetic waves that originated in the electrodynamics of Faraday and Maxwell. Electromagnetic field pervades the whole Universe.

​

Michael Faraday who had done many experiments on electromagnetic phenomena conceived the idea of the electromagnetic field. James Clerk Maxwell gave a precise formulation of the dynamics of the electromagnetic field through his mathematical equations.

​

Important results followed from Maxwell's equations. Maxwell proved from his equations that electromagnetic waves exist and that their speed is
3,00,000 kilometers per second. This speed is the same as the speed of light already determined by scientists. So Maxwell concluded that light
is an electromagnetic wave. This is an important discovery. For, until then the nature of light had remained as a puzzle. 

 

After that, Hertz proved the existence of the electromagnetic waves in experiments. Then, Jagadish Chandra Bose and Guglielmo Marconi developed the methods to produce the electromagnetic waves and their uses.

​

Michael Faraday and James Clerk Maxwell who are the creators of the electromagnetic field are two of the greatest scientists the world has produced. Their life stories and achievements are very interesting.

​

What a contrast between Faraday and Maxwell as far as their births, growth, and education are concerned? One, Faraday, was born and grew up 
in a poor family. He had to leave his school in his 12th age and go for work. He was employed as a worker in a book-binding shop. He read all
the books that came for binding. The interest in Science that was created in him through that made him the greatest experimental scientist
the world has ever seen.

​

Maxwell was born in a rich family that owned 1500 acres of landed property. He went to college and university. There was no need for him to earn money. But impelled by an inner desire he devoted himself to scientific research.

​

It is through the achievements of these two that the world came to know the electromagnetic field. As a result, science and engineering progressed. It is the purpose of this essay to describe these things. 

Michael Faraday (1791-1867)

His life

Michael Faraday was born on 22 September, 1791 in a small town called Newington Butts in England. He was the third among the four children of James Faraday and Margarate Hotswell.

​

Faraday's parents belonged to the Christian sect called Sandemanians. Following the tenets of that sect, they rejected the riches and pleasures of the world. Michael also followed that throughout his life. He declined to accept England's highest honor of the title "Sir". Twice he refused to become the President of Royal Society. He had instructed that after death he should not be buried in the Westminster Abbey where all famous personalities were buried. He declined the invitations to attend the funeral ceremony of the Duke of Wellington and the wedding ceremony of the daughter of Queen Victoria.

​

When he was four years old, his family moved to the western end of London. His father got a job in an ironsmith's workshop. The family life proceeded in poverty. Faraday learnt writing, reading and a bit of arithmetic in a government school there. No higher education. When he was thirteen, he was was employed as an errand boy in a bookshop.

​

Through his hard work and capabilities, he earned the goodwill of the owner of the bookshop. The owner taught him bookbinding and other work and arranged for Faraday's lodging and boarding in his own home. 

​

Faraday began to read the books that came for binding. Books on Science attracted him. In the year 1809, he started to write in his own journal called Philosophical Miscellany. He took notes from the books that he read and recorded them in his journal. Science sections of the Encyclopedia Britannica, Conversation in Chemistry by Jane Marsette, Improvements of the Mind by James Watts are some of these books.

​

An important feature of Faraday's journal is the serial number system. He gave a number to every para of the journal. These serial numbers started as number 1 in the year 1832 and continued for 28 years. The number of his last para written in 1860 is 16,041.

​

Although he learnt the art of bookbinding well and worked in that, his mind sought Science only. During those days, it was difficult to get a paying job in scientific research. It requires great courage to leave a paying job in the hope of doing Science. His mother had great faith in God and gave courage and encouragement to her son, leaving everything to the Almighty.

​

An important turning point occurred in Faraday's life in the year 1813. That was his meeting with the famous scientist Humphry Davy. Let us hear that story through Faraday's words.

​

" When I was working in the bookshop, I was very eager to do experiments in Science.
I did not like commerce. A friend took me to listen to Sir H Davy's lectures in the
Royal Institution. I took notes of that lecture and then expanded the notes properly.

​

I considered that commerce was done for self interest and hence was bad. I wanted
to escape from that and work in Science which served served humanity at large. So
I became bold enough to write to Sir Davy. I explained my eagerness to do Science
and requested him to help me if opportunity arises. With that letter I sent him
my notes of his lectures. Davy asked me to come and see him. He said that the job
of an assistant in the laboratory of the Royal Institution."

​

This happened in the year 1813. He joined in the job the same year. He accompanied Davy on his European tour. Until the end, he was doing scientific research in the Royal Institution. Step by step he went higher and became a scientist par excellence.

​

Faraday married Sara Bernard in 1821. He breathed his last on 25, August 1867.

​

The discoveries of Faraday

At that time only a little was known about atoms. Electrons had not been discovered. However, it is better to explain and understand the discoveries of Faraday and Maxwell through atoms and electrons. Therefore, in Box-1, we have given a little about atoms, electrons, electric charge and electric currents.

​

​

​

​

​

​

​

​

​

​

​

              Box-1: Electric charge and electric current
   
Two scientists Oerstead and Ampere had discovered that if an electric current passes through a wire, a magnetic compass placed nearby is deflected.  A magnetic field is generated around the wire. This phenomenon greatly attracted Faraday. It induced him to think further. If electricity can produce magnetism, will magnetism produce electricity? He wrote in his journal as follows: "If it is possible to convert electricity into magnetism, why cannot the opposite transformation be done?" He tried many experiments to do this opposite transformation, but nothing
worked.

​

He succeeded only after many years. In August 1831, he started many new experiments to answer this question. He wound wires on opposite sides of an iron ring. If an electric current is passed in one wire, he found electric current is induced in the other wire. If there is a steady current in the first wire, there was no current in the second wire. Only during the starting and stopping of the current in one wire, current flowed in the second wire. Faraday concluded that a time-varying current in one wire induces a current in another wire in the neighborhood. This discovery of
Faraday is called electromagnetic induction and this is the basis of the transformer that is used today.

​

On 17 October of the same year Faraday's ambition was fulfilled. When he inserted or took out a bar magnet into a coil of wire he found  that current flowed in the wire.

​

The experiment continued in many forms over many days. He placed a copper disc in between the north and south poles of a bar magnet. He found that if that disc is rotated, an electric current is generated. This happened on 28 October 1832. This is the dynamo or electric generator. Today all the generators that generate electricity from waterfalls, windmills or nuclear power work only in the way Faraday discovered on that day.

​

The truth that a magnetic field exists all around a bar magnet can be made visible if we spread iron filings around the magnet. This is a very useful device for students to learn about magnetism. It was Faraday who discovered this way of making the magnetic field visible. Not only that. Faraday is the author of the idea that the invisible magnetic and electric fields exist in the world exactly like all the visible material objects. He saw in his mind's eye how this electromagnetic field spreads and how the field lines start from charged objects and magnets and spread everywhere and 
wrote a vivid description. Maxwell who came later gave a precise mathematical form to what Faraday saw in his mind's eye.

​

Since he succeeded in discovering and establishing the connection between electricity and magnetism, he was enthused to travel further along this path. The next stage was the connection between electromagnetic field and light. After many attempts, he succeeded in that. He discovered that if light is passed through a magnetic field, its polarization changes. This is called Faraday rotation. The relationship between electromagnetic field and light became completely clear only after Maxwell's discovery that light is an electromagnetic wave. 

​

Next he raised the question whether there is any connection between electromagnetic force and gravitational force and tried to answer it through many experiments. But he did not succeed. Until today nobody has found the answer. But Faraday's thought, that all the forces of nature are connected, has become today's important goal of physics research in the name of "Unification of the Forces of Nature".  

        

Other discoveries and more achievements of Faraday

Faraday's laws of electrolysis

When electric current is passed through a liquid, the liquid separates into its two parts. This is called electrolysis. Faraday performed many experiments in electrolysis and established two laws. They are called Faraday's laws of electrolysis. If one analyses these laws, it will become clear that electricity is made of electrons. This basic truth is hidden in these laws. One can therefore realize the importance Faraday's electrolytic
research from a fundamental point of view.

​

Faraday cage

This is a cage made of closely knitted wires. Faraday constructed this and proved that electric field cannot penetrate inside the cage. Faraday cage is a device which is used in laboratories even today.

​

Davy's safety lamp

Davy made this safety lamp with assistance from Faraday. Many dangerous explosions due to methane gas in mines were prevented by the use of this lamp. Thousands of mine workers were saved.

​

Faraday's lectures

Faraday's another great service was his lectures in Science. These lectures contributed not only to an income for the Royal Institution where he worked but also to the fame of that institution. Two series of lectures that he started - Friday evening lectures and Christmas lectures are continuing even today. Faraday lectured without a break from 1826 to 1861. More than a thousand people listened to his lectures. He was 
considered as a great Science lecturer. His Christmas lectures were given especially for young people. His lectures were brought out in the form of books. "The Chemical History of a Candle" is a book that benefits students even today.  

​

James Clerk Maxwell

His life

James Clerk Maxwell was born in June 1831 in Edinburgh in Scotland as the only son of John Clerk Maxwell and Frances Kay. John Clerk Maxwell was an advocate and the owner of Glenlair which was an estate consisting of 1500 acres of land. It was a wealthy family, but a cultured family that did not lose its mind because of its wealth.  

​

In the early life of James devotion to God plated an important part. Everyday morning the family and the servants got together and prayed. Every Sunday, they went for the church service eight kilometers away.

​

Maxwell's mother started teaching him at a very early age. But Maxwell did not omit playing with children of the neighborhood. In his house for ever there will be music and dance. There was never any shortage for laughter and joy.

​

The family's happy life came to an end in 1839. His mother Frances Kay died. The education of the eight-year old boy ran into trouble. He joined a school called Edinburgh Academy through the help of Jane who was Frances Kay's sister.

​

During the school period, Maxwell stayed with his aunt Jane for some time. Jane paid attention to the growth of Maxwell's devotion to God. He used to take the boy to the Church every Sunday and made him listen to the lectures of the priest in the School connected to the Church. Maxwell's unassuming devotion became his guide in later life.

​

Maxwell wrote his first scientific article at age fourteen. When he was sixteen he passed out of Edinburgh University and then succeeded in passing the reportedly difficult Tripos examination of Cambridge University.

​

First in Aberdeen University of Scotland and then in King's College of London, he was appointed as Professor.

​

After his father's death he had to look after the Glenlair estate. He managed that while being the Professor of the University. Although for some time he resigned the Professorship and devoted full time on the estate, he rejoined as Professor. He was appointed as the first Cavendish Professor of Cambridge University. He developed Cavendish Laboratory into a world-famous institution.

​

In 1858, Maxwell married Catherine Mary. He died in 1879 when he was only 48. His achievements during a short life take away our breath.    

  

Maxwell's equations for the electromagnetic field

Maxwell's greatest achievement is his equations for the electromagnetic field. They are given here:

 

 

             

 

 

 

 

 

 

 

 

 

 

                                Box-2 Maxwell's equations

​

These equations discovered by Maxwell in 1865 dictates the dynamics  of the all-pervading electromagnetic field. Through his mathematics Maxwell gave a precise mathematical form to the discoveries of Oerstead, Ampere and most importantly Faraday. 

 

But before he discovered these equations, he employed various other devices to understand the dynamics of the electromagnetic field. He imagined wheels and smaller wheels between them all over empty space. The electric and and magnetic fields were imagined to be
generated by the rotations of these wheels. Maxwell could interpret all the experimental results of Oerstead, Ampere and Faraday in terms of these rotations. Thus Faraday's electromagnetic field and lines of force are the rotations of invisible wheels in space.

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

                 Box-3: Vectors

​

​

​

​

There is no need to understand these equations when reading this essay. But they are given here only to emphasize that " All Laws of Nature are given in the language of Mathematics". These is no Science without Mathematics. Those who want an explanation of the equations in Box-3 can read it in Box-4.

​

         

 

 

 

 

 

 

 

 

 

 

 

 

                 Box-4 Meaning of Maxwell's Equations

​

The most important consequence of these equations was already mentioned in the introduction to this essay. Maxwell proved from his equations that there are waves in the electromagnetic field and he could calculate the speed of those waves. There were a few quantities needed to calculate the speed and Maxwell himself measured those quantities experimentally. Thus he determined the speed to be 300,000 kilometers per second. Since the speed of light was known to be that number, Maxwell could discover that light is an electromagnetic wave. Thus the question "What is light?" that was being asked for hundreds of years since the time of Newton was answered by Maxwell.

​

How the name and the nature of the electromagnetic wave changes according to the wavelength is explained in Box-5.

​

​

​

​

​

​

​

​

​

​

​

         

               

 

                 Box-5 Spectrum of electromagnetic waves

​

Other discoveries of Maxwell

Maxwell's law of distribution of velocities

In the Kinetic Theory of Gases, Maxwell made an important discovery. Molecules in a gas are moving with a speed of about 0.5 kilometer per second. Not all the molecules have the same speed. Some with smaller and some with larger speed. How are the speeds distributed? Maxwell gave a mathematical answer to this question. This is called Maxwell's law of distribution of velocities. This is an important discovery. Even today, in any research on the speeds of molecules, it is this law that is used. Even if Maxwell had not discovered his equations for the electromagnetic field, this law alone would have established his name in the world of Science. The famous scientist Ludwig Boltzman started from Maxwell's law and extended it. It is called Maxwell-Boltzman distribution.

​

Let us consider the gas in a container or the air in a room. Although the speeds of the molecules are distributed, there is an average speed. It is this average speed that determines the temperature of the gas or air. If the average speed is larger, the temperature will be larger.

​

Thermodynamics or the science of heat is the physics of the thermal properties of gases and other objects. Maxwell's discoveries in the kinetic theory of gases  provide us with an important route to understand thermodynamics.
 
Maxwell's demon

Maxwell employed a trick to explain the relationship between thermodynamics and kinetic theory. Consider a box containing air at some particular temperature. It may be 30 degrees Celcius. So the average velocity of the molecules may be some specific number.

​

Let us suppose that there is a partitioning wall that divides the box into two parts. Make a tiny hole in the partition and fix a tiny door which can close the hole. Imagine a demon capable of seeing individual molecules standing guard at the door.

​

Through the hole, molecules will be running from left to right and from right to left. Let the demon admit the molecules from left to right to go through the holes if their velocities are higher than the average velocity and admit those going from right to left if their velocities are lower than the average velocity. The other molecules are prevented by closing the door and so after collision with the door run with the same speed but in 
opposite direction.

​

So the average velocity on the left side will go on decreasing while that on the right side will go on increasing. Correspondingly, the temperature on the left will decrease and on the right will increase. It means that heat will be passing from a place of lower temperature to a higher temperature.

​

This does not happen in nature. Heat always passes from a body of higher temperature to a body of lower temperature. This is what happens and this is one of the Laws of Thermodynamics. How does Maxwell's demon succeed in going against this Law?  This trick of Maxwell is keeping
not only the students of Thermodynamics but even the experts debating hard.
   
What are Saturn's rings made of?

The rings around the planet Saturn were a puzzle for 200 years. Maxwell studied the rings through mathematics and proved that they cannot be made of solids, liquids or gases. Hence he concluded that they are made of small dust particles. Maxwell was awarded Adam's
Prize for this work. The Astronomer Royal Sir George Airy praised this mathematical physics achievement of Maxwell very highly. Today the world has accepted this answer found by Maxwell 150 years ago.

​

Electromagnetic field and beyond

Einstein said that " The greatest discovery of Physics is Faraday's electromagnetic field". The reason for his statement is that Newton formulated the laws for material bodies that we see. But Faraday discovered the electromagnetic field that exists everywhere but we cannot see. Electromagnetic field also exists just like the table and chair that we see. The field exits everywhere and all the time. The electric field vector and the magnetic field vector are dancing about at great speed. For instance, when we press the button in our cell phone these fields announce their presence.

​

There is another reason why Einstein said that. He changed Newton's gravitational force and created the laws of the gravitational field that obey his General Theory of Relativity. These laws of gravitational field were similar to Maxwell's laws for the electromagnetic field. So one can say that Faraday's electromagnetic field showed the way for Einstein's gravitational field.

​

Maxwell proved the existence of electromagnetic waves from his equations. In the same way, Einstein proved the existence of gravitational waves from his equations in the year 1916. Almost 100 years later, in 2015, these gravitational waves were detected by the wonderful instrument called LIGO in USA.

​

For more than 150 years Maxwell's laws have stood the test of time. Even the two revolutions of Quantum Mechanics and Relativity that shook the foundations of Physics did not change Maxwell's equations.

​

In the great contradiction between Newton's Dynamics of Matter and Maxwell's Dynamics of Fields, Einstein argued that it is Maxwell's laws that are correct and so changed Newton's laws. This is how the theory of relativity connecting space and time was born. Thus one can say relativity was born from Maxwell's equations.

​

Quantum Mechanics also did not change Maxwell's equations. But the inner meaning of the field underwent an important change. It was found that the energy of the field will manifest as tiny packets, called quanta. These packets of energy are the photons which are the particles of light. Thus originated Quantum Field Theory which is the basic language of the Standard Model which underlies all of Fundamental Physics.

​

Higgs boson that was discovered in 2012 is the quantum of the Higgs field. This Higgs field pervades all of space and gives mass to all elementary particles incuding electron. Thus, the concept of the field that was born in the mind of Faraday as a result of his researches has evolved into one of the deep ideas of Physics.

​

One can say that the first invisible field that was discovered is atmosphere. But it is in fact not a field. It is made of gases like Nitrogen and Oxygen. Atmosphere extends only to a height of about 20 kilometers. Electromagnetic field, Higgs field and many other fields that one encounters in the Standard Model are really fields. According to Einstein's General Theory of Relativity, gravitational field is the curvature of space-time.

​

There are a few more invisible things, like neutrinos, Dark Matter and Dark Energy. But neutrinos are particles and Dark Matter may be particles. Dark Energy may be a field. Nothing much is known about Dark Matter and Dark Energy.

​

Concluding remarks

This essay has been written with the idea that students and their parents will read it.

​

* Lessons to be learnt from Faraday's life:  Enthusiasm and hard work will make you a scientist.   Even higher education is not necessary. Lessons to be learnt from Maxwell's life: Wealth   need not be an obstacle to becoming a scientist; it may be helpful.   
 
* It is the basic research that Faraday and Maxwell did 150 years ago that led to all the electrical,   electronic and communication technology that we use. "Every discovery in basic research will   lead to applications later", said Homi Bhabha. There are still many more discoveries in basic
  science that are to be made. Nevertheless it is often asked "What is the use of this research?"   Laymen, students, government bureaucrats - all of them ask such questions. Definitive answer  is provided by the story of Faraday, Maxwell and electromagnetic field.

​

* Every time you use the cellphone, think a little about Faraday, Maxwell and the all-pervading   electromagnetic field which is their gift to us.

​

* Before you buy a cellphone for your daughter or son, ask them to think and learn how this small gadget brings the distant speaker's voice.   

References

1. Ten physicists who transformed our understanding of reality, Rodri Evans and Brian Clegg, Running Press Publishers, London.

2. The Philosopher's Tree (Michael Faraday's life and work, in his own words),Peter Day, Institute of Physics Publishing, 1999.

3. James Clerk Maxwell, CWF Everitt, Charles Scribner's sons, New York, 1975. 

4. The life of James Clerk Maxwell, Lewis Campbell and William Garnett, Macmillan and Co, London, 1882.