Maxwell's Electromagnetic Theory of Light Propagation


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The Scottish physicist James Clerk Maxwell contributed a great deal to the field of physics during the 1860s, with his theories on magnetism, optics and electricity completely transforming the realm of scientific discovery. As a result, Maxwell's findings have since been deemed the second great unification in the field of physics.

A Dynamical Theory of the Electromagnetic Field

Maxwell’s most significant scientific achievement was his electromagnetic theory of light propagation which he first presented in 1864 with the publication of ‘A Dynamical Theory of the Electromagnetic Field’. This paper hypothesised that an electric field, a magnetic field and light could all be explained with the using a single theory.

The publication of A Dynamical Theory of the Electromagnetic Field was made possible by several earlier research projects which had failed to gather the same level of attention from members of the scientific community.

Early Inspirations

An early inspiration for Maxwell's work took place in a Copenhagen in 1820, when Hans Christian Oersted embarked on a series of experiments in which he hoped to illustrate the connection between magnetism and electricity. This prompted several ‘copycat’ experiments from other physicists, all hoping to discover the fundamental nature of this mysterious connection.

A decade after Oersted's experiment took place, Michael Faraday converted electric energy into magnetic energy using an insulated wire and a galvanometer. Faraday used this experiment as inspiration for ‘On Faraday's Lines Of Force’, a paper in which he derived electric and magnetic equations by comparing the flow of liquid to lines of electrical and magnetic force.

A Single Unified Theory

Maxwell understood the significance of Faraday's work and realised that the speed of an electromagnetic waves travelled at the speed of light. As a result, he was able to incorporate light, magnetism and electricity into a single theory.

Maxwell further concluded that light propagated in electric and magnetic waves, which he believed would vibrate perpendicular to one another.

Following this discovery, Maxwell revised his papers and gathered the findings, eventually publishing them together in his 1873 ‘Treatise on Electricity and Magnetism’.

Maxwell's electromagnetic theory of light propagation eventually paved the way for a number of major technological innovations.

The first and possibly most significant of these occurred in 1888, when Heinrich Hertz used Maxwell's theory to create instruments capable of sending and receiving radio pulses.

This discovery, contributed to the creation of the television and the microwave and without Maxwell's tireless efforts, many of the modern conveniences upon which society has come to depend would not exist.

As such, James Clerk Maxwell truly is the champion of modern day science.

Sources and Further Reading


This article has been produced in association with the Pittcon Conference and Expo to celebrate the International Year of Light 2015.

For more information on how Pittcon are involved in IYL 2015, please visit



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