Benjamin Franklin

B enjamin Franklin was a great American statesman, writer, and inventor but he was also an early investigator of electricity. Franklin realized that electricity could be explained just as easily with one fluid as with two. Positive charge could be considered to be an extra amount of the fluid. Negative charge would then be a shortage of the same substance. The fluid theory didn’t last, but Franklin’s idea of positive and negative charges being two sides of a single force did.

Franklin also recognized a very important law of electricity: the law of conservation of charge. It says that for every negative charge created, there must be an equal amount of positive charge. That means that the total of all positive and negative charges in the universe must balance each other perfectly.

The law of conservation of charge doesn’t mean that we can’t have any electricity. But whenever we unbalance electrical forces, we must create positive and negative charges in equal amounts. For example, you can create an electrical charge by rubbing an inflated balloon against a wool sweater. The balloon will pick up a slight negative charge from the wool. But the wool will also receive an equal amount of positive charge. The balloon will then stick to a wall because of the difference in electrical charge between the wall and the balloon.

Hans Christian Orsted

T he next important discovery about electricity was made by Hans Christian Orsted in 1820. He connected a wire to a battery to make an electric circuit. A magnetic compass happened to be sitting on the laboratory table nearby. Orsted noticed that when electricity was flowing through the wire, the compass needle was attracted to it.

After more experimenting, Orsted was sure of his discovery: a moving electrical charge creates magnetic force. Whenever an electric current flows through a wire, it creates magnetic forces around the wire.

After 1820 the study of electricity and magnetism moved at a very rapid rate. Orsted had found that electricity could exert enough force to make a magnetic needle spin in a compass. Stronger electric currents and stronger magnets could be combined to spin a motor. Using Orsted’s discovery, the first electromagnet and the first electric motor were both built by 1823.

Michael Faraday

M ichael Faraday was born in a small village near London. His father, a poor blacksmith, could feed and clothe his family with difficulty but was entirely unable to afford the luxury of an education for his boy. Michael had to work, and he had to learn a trade. When a boy of 13, he became an errand-boy and later on a bookbinder’s apprentice.

Some of the scientific books passing through his hands aroused the boy’s interest in science.

Finding the apprentice studying electricity, a visitor to the bookbinder’s shop gave him tickets to attend four lectures by Humphry Davy. While at the lectures, Faraday listened, understood everything and put down every word. Then, at home, in his room, he wrote Davy a letter, telling him of his great interest in science and his desire to do scientific work. The notes of the lectures were enclosed as proof of his earnestness.

They say that Davy was a scientist well known for his researches and discoveries but his greatest discovery was Michael Faraday.

In March 1813, Davy took him as a laboratory assistant at the Royal Institution. Later he assisted Davy in his research, started to write articles for scientific magazines and to carry on experimental work.

In his lifetime, Faraday performed more than two thousand laborious experiments and made countless valuable discoveries in chemistry and physics.

One of his most important discoveries is the generation of electricity from magnetism. On the very day on which the report of Orsted’s discovery was published in England, Faraday repeated the latter’s experiments and confermed his results. Even at that early date, the fact that electricity could produce magnetic effects turned his thoughts towards the reverse possibility – that of generating electricity owing to magnetic effects.

Faraday wound a copper wire into a coil, and to this wire he connected a galvanometer in order to detect any current which might be generated. He observed the galvanometer needle move both while plunging a bar magnet into the hollow coil and while lifting it out. Evidently, electricity had been produced in the coil. But why had his previous experiments failed? It was because his magnets, wires, and coils had been stationary. It was only when the magnet was moving that an electric current was generated. When the magnet was still, no electricity flowed. From this experiment came what is known as Faraday’s law: a moving magnetic field creates an electric current in a wire.

As known all over the world, on October 1831, Faraday made his historic discovery, namely, induction of a current in a conductor resulted when the conductor was made to cut the lines of magnetic force.