Refraction Power-Point Power Point 10-3
Definition • Refraction- the bending of a wave or particle as it passes from different mediums
Application • A fish appears higher than it actually is…
Bending Toward the Normal • When light goes from a less dense to more dense medium, it is bent toward the normal. This is an example of air going to fiberglass.
Bending Away from the Normal • When light passes fromfiberglassto air, it bends away from the normal.
The index of refraction (n) • The speed of a wave is slower in a more optically dense medium.
A relationship… • The relationship between the index of refraction (n) and the speed of the wave can be determined by • Example 1: What is the speed of light in a diamond (n=2.42)? where c=3 X 10 8m/s
Snell’s Law • There is a mathematical relationship between: • n= index of refraction for a material • Angle of incidence • Angle of reflection Example 2: What is the angle of refraction of light going at an angle of 10 o from a diamond (n=2.42) to air (n=1.0)?
Total Internal Reflection • Only occurs when light goes from more dense to less dense. • Three cases: • (1) Refracts- bends away from normal (o-43o) • (2) Critical angle- prism • (3) Reflection • Example 3: What is the maximum angle of incidence in a diamond where refraction occurs? (the angle of refraction is 90o or the critical angle)
Applications of Refraction • Fiber optics, polar bear skin, sparkling of diamonds
Example 4: Double Refraction • A layer of oil (n=1.45) floats on water (n=1.33). A ray of light has an incident angle with the oil of 40o. What is the angle that the ray travels in water?
Equilateral Triangle Prism • Since speed of wave is slowing in glass (n=1.52) • Red is longest wavelength (700 nm); lowest frequency; bends the least. • Violet is the highest wavelength (400 nm); highest frequency; bends the most.
Example 5:Angles in Equilateral Triangle • It is observed experimentally that the angle resulting in a prism is 41.5 o in crown glass (n=1.52). Determine the angles in the diagram provided.