On 13/05/2019 19:59, \0xDynamite wrote:
If light travels at a. different speed for different colors in order
to account for the rainbow of a prism, how fast is the. speed of light
then? Is there real physics to optics? How can light know what
direction to bend after it leaves the lens?
The speed of light in glass is slightly less than the speed of light in
air. This causes light to be refracted (roughly speaking, change the
direction of its path) when it enters glass at an angle.
The mathematics of this is called Snell's law, sin(a)/sin(b) = v(a)/v(b)
where sin(a) is the angle of incidence, sin(b is the exit angle, v(a) is
the velocity of light in air and v(b) is the velocity of light in glass.
Thanks for your response. The problem with Snell's Law, AFAIK, is
that there are actually two angles of incidence to account for since
there are two dimensions to its surface.
No, there is only one angle between a line and a plane.
However, light of different frequencies travels at different speeds in
glass. Thus blue light bends more than red light, and if the light
travels through a triangular prism the familiar spectrum is formed.
Yes, this is the part where science "fills in the gaps" it seems
without just cause. Is light a physical constant > dependent on
material properties
The speed of light in a vacuum is constant. The speed of light in glass
depends on its wavelength.
This is known as dispersion. The amount (and direction) of the
dispersion depends on the type of glass.
or is the lens effecting different frequencies differently
Yes
> or does light change speed for the viewer.
No.
I think the only way to account for the axiis of a lens (even though
it may be symmetrical), is through the relationship to the viewer.
Ie. it is both subjective and objective phenomenon.
now you have lost me
Peter F
Mark
