This is a schematic representation of the electromagnetic spectrum. Note that any laser which operates at wavelengths between 400nm and 700nm are all clearly within the visible range of the spectrum. Additionally, the shorter the wavelength, the higher the energy.
Electromagnetic waves can also be described as a stream of photons, which are particles without any mass, each travelling in a wave-like pattern and moving at the speed of light (in vacuum). Each photon carries a specific bundle of energy and travels at a specific wavelength. All electromagnetic radiation can be expressed in terms of photons. The only difference between the various types of electromagnetic radiation is the amount of energy found in these photons. Radio waves, for instance exhibit photons with low energies, whereas gamma rays, for instance exhibit photons with extremely high energies.
By definition, the electromagnetic wave is a self-propagating wave in space, which has both an electric and a magnetic wave component to it. These two wave components are in phase with each other and oscillate perpendicular to each other and to the direction of propagation. Electromagnetic waves are part of the electromagnetic spectrum. The electromagnetic spectrum is essentially the distribution of all electromagnetic radiation according to energy, wavelength of frequency. The entire electromagnetic spectrum can thus be expressed in terms of energy, wavelength or frequency. We have grown accustomed to specific types of electromagnetic radiation, such as gamma rays, x-rays, visible light, infrared light, microwaves and radio waves, just to name a few. Each one of these subdivisions falls into a specific energy (or frequency) range within the electromagnetic spectrum. In terms of wavelength the electromagnetic spectrum encompasses electromagnetic waves from several thousand kilometers in length down to the equivalent of the diameter of proton (some scientists will even go further and set the smallest wavelength equal to the Planck Length, which is 1.6 x 10-35 meters).
The Electromagnetic Spectrum
