Light of wavelength 500 nm in air enters a glass block with index of refraction n=1.5. When the
light enters the block, which property of light does not change?
If energy is conserved, the frequency must remain the same
What Determines Color?
The wavelength of a light wave is 700 nm in air; this light appears red.
If this wave enters a pool of water, its wavelength becomes:
λ = λair.33 = 530 nm
If you are swimming underwater, this light still appears red.
Given this, what property of a light wave determines its color?
θ = sin (1 )
What are the critical angles for
Water (n=1.33) – 48°
Diamond (n=2.42) – 24°
Mirages are caused by total internal reflection.
Making a Rainbow
The sun is behind your back when you see a rainbow.
Dispersion causes different colors to refract inside water droplets at different angles.
Most of the light refracts into the air at the back of the droplet, but a little reflects back
into the drop.
Dispersion separates the colors even more as the rays refract back into the air. Seeing a Rainbow
You see a rainbow with red on the top, violet on the bottom.
Red light is refracted predominantly at 42.5°. The red light reaching your eye