Maxwell went on to reason that invisible electromagnetic waves exist beyond the visible and ultraviolet light spectra, but sadly he did not live long enough to test his idea. Maxwell died in 1879, not long after developing his theory.

Visiblelightwavelength

Maxwell was interested in a multitude of scientific problems that included electricity and magnetism. He first published articles on these subjects in 1855, then compiled his work in 1873 into a book entitled Treatise on Electricity and Magnetism, which is now considered a classic in the field of matter.

In 1863, Maxwell discovered that by manipulating equations for electricity and magnetism, it was possible to extract a value that corresponded to the speed of light. Surprised by this result, he began to suspect that light, electricity and magnetism were one and the same.

Electromagneticspectrum

Today, the electromagnetic spectrum is known to extend far beyond the colours of the rainbow, as shown in the diagram below.

Speedof light

Hertz labelled these new waves “radio waves”, and their discovery was put to beneficial use in the development of the telegraph and the radio.

Lightspectrum

The electromagnetic spectrum is the distribution of electromagnetic radiation according to frequency or wavelength. Thus, visible light, gamma rays and microwaves are really the same thing. They are all electromagnetic radiation; they simply differ in their wavelengths.

Although other electromagnetic waves – radio waves, infrared light, ultraviolet light, X-rays and gamma rays – represent “colours” that are invisible to us, they are nonetheless forms of light.

The electromagnetic spectrum is continuous but scientists have divided it in an artificial manner for practical reasons. The divisions were mainly established by the limitations of the various techniques used to detect wavelengths. For example, the limits of the visible light range is defined by what our eyes can detect.

Electromagneticspectrum wavelength

The year of 1888 provided the consecration of Maxwell’s work when the German physicist Heinrich Rudolf Hertz succeeded in demonstrating three important facts: that electricity can be transmitted by electromagnetic waves, that these waves travel at the speed of light, and that their wavelengths are a million times the length of visible light and ultraviolet waves.

To follow up on this idea, he developed new equations for electricity and magnetism and concluded that not only is light a wave – as demonstrated by Thomas Young more than 50 years earlier – but an electromagnetic wave. The discovery that light possesses both electric and magnetic components proved to be of paramount importance.

Visiblelightspectrum

The electromagnetic spectrum is something that is more familiar than one might think. The light that our eyes can see is actually part of the electromagnetic spectrum. This visible part of the electromagnetic spectrum consists of the colours we see in a rainbow - from reds and oranges, through blues and purples. Each of these colors actually corresponds to a different wavelength of light.

The portion of the electromagnetic spectrum that we can see with our eyes is tiny with respect to its full extent. If the electromagnetic spectrum was a window 30 million kilometres long, we would only have to open it three centimetres to let in all the visible light.

Our understanding of the nature of light took a giant leap forward in the second half of the 1800’s with the help of the Scottish physicist James Clerk Maxwell.

The main picture represents the electromagnetic spectrum. Click the red dots in the spectrum to see images or representations of the frequency chosen.