Reflection, Refraction, and Dispersionwestfieldgeometry.weebly.com/uploads/1/0/8/8/... ·...
Transcript of Reflection, Refraction, and Dispersionwestfieldgeometry.weebly.com/uploads/1/0/8/8/... ·...
The Physics of Rainbows!
Reflection, Refraction, and
Dispersion
Energy of Light
Ray Diagrams of Light
Light travels in a straight line until it encounters a boundary.
In which case, light can either reflect or transmit through the
boundary. Sometimes it does both.
Wave front is the plane where all the light is traveling at the
same speed and are in phase.
Reflection
In the case of specular reflection, light “bounces off ” the
surface similar to how a basket ball bounces off a smooth
surface.
In the case of diffuse reflection, light “bounces off ” the same
way as above but this time the surface has large rocks on it.
θi= θr where i stands for incident and r stands for reflected.
Reflection
Refraction
Refraction
n1= 1.00
n2= 1.33
From a lower to higher index of
refraction, transmitted light bends
toward normal
Refraction
n2= 1.00
n1= 1.33
From a higher to lower index of
refraction, transmitted light bends
away from normal
These are the Equations Used to Calculate
how much Light is Transmitted and Reflected
Dispersion
Dispersion is the dependence of wavelength for the index of
refraction.
Colors of light have different wavelength and thus index of
refraction. Red moves the fastest with purple moving the
slowest.
ROYGBIV
Red’s wavelength is the longest and Violet’s is the shortest.
Happens in refraction as shown by prism in book and at
http://phet.colorado.edu/en/simulation/bending-light
This allows us to see the visible spectrum.
Huygen’s Principle
Essentially: A new wave front is tangent to wavelets. What
this is used for is to prove Snell’s Law.
http://phet.colorado.edu/en/simulation/bending-light
Total Internal Reflection
TIR
n2= 1.00
n1= 1.33
From a higher to lower index of
refraction it is possible to have TIR
occur if the angle is right.
Fiber Optics
If TIR didn’t happen then fiber optics would be impossible.
What do you suspect the design of fiber optics to be?
Rainbow
What causes the rainbow is the combination of reflection,
refraction, dispersion, and TIR. With the shape of the
raindrop this can only occur at a very select angle of entry to
the raindrop. That is why you usually only see one rainbow.
But sometimes it is possible to see a faint Double Rainbow.