Public Lab Wiki documentation

How Light Works

Visible light has a wavelength in the range of about 380 nanometres (nm), or 380×10−9 m, to about 740 nanometres. Every color that we see corresponds to a different wavelength, from the very long (red to orange - 600-700nm) to short (violet to ultraviolet - 440-360 nm). Beyond that, you have the rest of the electromagnetic spectrum, stretching in each direction as far as the eye can see -- or can't see, as the case may be. Visible light makes up a very small portion of the electromagnetic spectrum.

(courtesy of wikipedia)

All of the light we perceive falls within that tiny range. One thing that's interesting here: you'll notice that white light doesn't show up on the image above. That's because white light isn't actually a color - it's all the colors mixed together (or rather, they appear to be mixed, because full spectrum light activates all three types of cone cells in your eye - red green and blue). It's called additive mixing. Consequently, when you see white light, you are actually seeing the full color spectrum.

Here is a picture of a pretty standard form of visible light -- the sun!

If you take a prism and scatter the light from the sun, you can see the individual colors that make up white light. You can actually use a second prism to reassemble the spectrum i.e. turn it back into white light. Alternatively, you can look at the spectrum to get a much more precise idea of what wavelengths are present in your light source.

(courtesy of fdecomite)

Different kinds of white light

Incandescent

Fluorescent

White LED

Sunlight

How Light Works

Visible light has a wavelength in the range of about 380 nanometres (nm), or 380×10−9 m, to about 740 nanometres. Every color that we see corresponds to a different wavelength, from the very long (red to orange - 600-700nm) to short (violet to ultraviolet - 440-360 nm). Beyond that, you have the rest of the electromagnetic spectrum, stretching in each direction as far as the eye can see -- or can't see, as the case may be. Visible light makes up a very small portion of the electromagnetic spectrum.

(courtesy of wikipedia)

All of the light we perceive falls within that tiny range. Beyond that, it's radio waves, microwaves, X-rays, and all manner of other radiation.

One thing that's interesting here: you'll notice that white light doesn't show up on the image above! That's because white light isn't actually a color - it's all the colors mixed together (or rather, they appear to be mixed, because full spectrum light activates all three types of cone cells in your eye - red green and blue). It's called additive mixing. Consequently, when you see white light, you are actually seeing the full color spectrum.

Here is a picture of a pretty standard form of visible light -- the sun!

If you take a prism and scatter the light from the sun, you can see the individual colors that make up white light. You can actually use a second prism to reassemble the spectrum i.e. turn it back into white light. Alternatively, you can look at the spectrum to get a much more precise idea of what wavelengths are present in your light source.

(courtesy of fdecomite)

Viewed with a spectrometer, it should look something like this:

Different kinds of white light