Michael Faraday

Michael Faraday (September 22, 1791 – August 25, 1867) was a British scientist (a physicist and chemist) who contributed significantly to the fields of electromagnetism and electrochemistry. He also invented the earliest form of the device that was to become the Bunsen burner, which is used almost universally in science laboratories as a convenient source of heat.

Scientific career

His greatest work was with electricity. In 1821, soon after the Danish chemist, Hans Christian Ørsted 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. 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.

Related Topics:
1821 - Hans Christian Ørsted - Electromagnetism - William Hyde Wollaston - Electric motor - Mercury - Homopolar motor

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Ten years later, in 1831, he began his great series of experiments in which he discovered electromagnetic induction, though the discovery may have been anticipated by the work of Francesco Zantedeschi. 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.

Related Topics:
1831 - Electromagnetic induction - Francesco Zantedeschi

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

His demonstrations established that a changing magnetic field produces an electric field. This relation was mathematically modelled by Faraday's law, which subsequently became one of the four Maxwell equations. These in turn evolved into the generalization known as field theory.

Related Topics:
Faraday's law - Maxwell equations

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Faraday then used the principle to construct the electric dynamo, the ancestor of modern power generators.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Faraday proposed that electromagnetic forces extended into the empty space around the conductor, but did not complete his work involving that proposal. Faraday's concept of lines of flux emanating from charged bodies and magnets provided a way to visualize electric and magnetic fields. That mental model was crucial to the successful development of electromechanical devices which dominated engineering and industry for the remainder of the 19th century.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

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

Related Topics:
Chemistry - Benzene - Oxidation - Electrolysis - Anode - Cathode - Electrode - Ion

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

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. 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.

Related Topics:
1845 - Faraday effect - Diamagnetism - Polarization

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

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.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~