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Michael Faraday’s contribution into Physics

1. Michael Faraday is considered to have been one of the great scientists in history. Some historians of science refer to him as the greatest experimentalist in the history of science. It was largely due to his efforts that electricity became viable for use in technology. The SI unit of capacitance, the farad (symbol F), is named after him.

He was the first to link electricity to magnetism and then link magnetism back to electricity - i.e. he induced an electric current using magnets - thus inventing the dynamo, predecessor to today's electric generator.

2. In 1821, soon after the Danish chemist, Hans Christian Orsted discovered the phenomenon of electromagnetism, Davy and William Hyde Wollaston tried but failed to design an electric motor. Faraday, having discussed the problem with the two men, went on to build two devices to produce what he called electromagnetic rotation: a continuous circular motion from the circular magnetic force around a wire. A wire extending into a pool of mercury with a magnet placed inside would rotate around the magnet if charged with electricity by a chemical battery. This device is known as a homopolar motor. These experiments and inventions form the foundation of modern electromagnetic technology.

3. Ten years later, in 1831, he began his great series of experiments in which he discovered electromagnetic induction He found that if he moved a magnet through a loop of wire, an electric current flowed in the wire. The current also flowed if the loop was moved over a stationary magnet. His demonstrations established that a changing magnetic field produces an electric field. This relation was mathematically modeled by Faraday's law, which subsequently became one of the four Maxwell’s equations. These in turn evolved into the generalization known as field theory. Faraday then used the principle to construct the electric dynamo, the ancestor of modern power generators.

4. Faraday also dabbled in chemistry, discovering chemical substances such as benzene, inventing the system of oxidation numbers, and liquefying gases such as chlorine. He also discovered the laws of electrolysis and popularized terminology such as anode, cathode, electrode, and ion.

5. In 1845 he discovered what is now called the Faraday effect and the phenomenon that he named diamagnetism. The plane of polarization of linearly polarized light propagated through a material medium can be rotated by the application of an external magnetic field aligned in the propagation direction. This established that magnetic force and light were related.

6. In his work on static electricity, Faraday demonstrated that the charge only resided on the exterior of a charged conductor, and exterior charge had no influence on anything enclosed within a conductor. This is because the exterior charges redistribute so that the interior fields due to them cancel. This shielding effect is used in what is now known as a Faraday cage.