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- Faraday's greatest work was with electricity. In 1821, soon after the Danish chemist, Hans Christian Orsted, discovered the phenomenon of magnetism, Humphry 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 which is 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. Unwisely, Faraday published his results without acknowledging his
debt to Wollaston and Davy, and the resulting controversy caused Faraday to withdraw from electromagnetic research for several
years.
- 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. This was the first transformer (inductor), although Faraday used it only
to demonstrate the principle of electromagnetic induction and did not realise what it would eventualybe used for.
His experiments established that a changing magnetic field produces an electric field. This relation was mathematically
modelled by faraday's law, which afterwards became one of the four Maxwell equations. These in turn evolved into
the generalization known as field theory.
Faraday then used this principle to construct the first dynamo (in the
form of a copper disk rotated between the poles of a permanent magnet), the predecessor of modern dynamos and generators.
- In 1832, Michael Faraday reported that the quantity of elements separated by passing an electrical current through a molten
or dissolved salt was proportional to the quantity of current passed through the circuit. This became the basis of the first
law of electrosis. He also popularized terminology such as anode, cathode, electrode, and ion.
- In 1845 he discovered what is now called the Faraday effeact. 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. He wrote in his notebook, "I have at last succeeded in illuminating a magnetic curve or line of force and in magnetising
a ray of light". This established that magnetic force and light were related.
- In 1845 he also discovered the phenomenon that he named Diamagnetism - a very weak form of magnetism that is only
exhibited in the presence of an external magnetic field. This phenomenon can can be used for levitation.
- 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
such that the interior fields due to them cancel. This shielding effect is used in what is now known as a Faraday cage.
- Faraday also dabbled in chemistry, discovering chemical substances such as benzine, inventing the system of oxidization
numbers, and liquefying gases.
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