| Themes > Science > Physics > Optics > What is Light? > What is Light? |
Electromagnetic Wave Theory |
| Light is just one portion of
the various electromagnetic waves flying through space. The
electromagnetic spectrum covers an extremely broad range, from radio waves
with wavelengths of a meter or more, down to x-rays with wavelengths of
less than a billionth of a meter. Optical radiation lies between
radio waves and x-rays on the spectrum, exhibiting a unique mix of ray,
wave, and quantum properties.
At x-ray and shorter wavelengths, electromagnetic radiation tends to be quite particle like in its behavior, whereas toward the long wavelength end of the spectrum the behavior is mostly wavelike. The visible portion occupies an intermediate position, exhibiting both wave and particle properties in varying degrees.
In radiometry, light’s propagating wavefront is modeled as a ray traveling in a straight line. Lenses and mirrors redirect these rays along predictable paths. Wave effects are insignificant in an incoherent, large scale optical system because the light waves are randomly distributed and there are plenty of photons. |
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Like
all electromagnetic waves, light waves can interfere with each other,
become directionally polarized, and bend slightly when passing an edge.
These properties allow light to be filtered by wavelength or amplified
coherently as in a laser.