Help Why can't we see ultra-violet light?

[ecanescence-fan]

Help! Why can't we see ultra-violet light??

Homework Statement

Can someone please tell me in a nutshell why we can't see ultra-violet light??

Homework Equations

The Attempt at a Solution

 

[da_willem]

Most of the light emitted by the sun is what now for us is 'visible light'. Our eyes evolved to become sensitive for a range of light in which the sun emits the most. Ultra-violet is emitted far less by the sun than visible light, so it would not be that useful to be able to see this.

 

[Astronuc]

The eyes adapted to light in the 'visible' range. The cones react to particular color, and the optics of the lens do not favor UV.

http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html
http://en.wikipedia.org/wiki/Cone_cell
http://en.wikipedia.org/wiki/Rod_cell

http://hyperphysics.phy-astr.gsu.edu/hbase/vision/visioncon.html#c1


The other factor is the UV is generally absorbed rather than reflected. Bees and perhaps some other insects are sensitive to UV and certain flowers do reflect low frequency UV. So as da_willem mentioned, it is more beneficial for eyes to adapt to frequencies with more intensity.

http://hyperphysics.phy-astr.gsu.edu/hbase/vision/solirrad.html#c1
http://hyperphysics.phy-astr.gsu.edu/hbase/ems3.html#c3

The sun is a strong source of ultraviolet radiation, but atmospheric absorption eliminates most of the shorter wavelengths. The eyes are quite susceptible to damage from ultraviolet radiation. Welders must wear protective eye shields because of the uv content of welding arcs can inflame the eyes. Snow-blindness is another example of uv inflamation; the snow reflects uv while most other substances absorb it strongly.

 

[DaveC426913]

"...Snow-blindness is another example of uv inflamation; the snow reflects uv while most other substances absorb it strongly..."

Huh. Now I know.