REFRACTION

REFRACTION OF WAVES Refraction: A change in the direction of waves as they pass from one medium to another, or of water waves as they encounter a depth change

REFRACTION OF WAVES The diagram shows how waves are refracted and how the velocity and wavelength change. Recall that as waves enter a medium with differing properties, the velocity will change. As water encounters a depth change, the velocity will change. V 2, λ 2 V 1, λ 1

REFRACTION OF WAVES The change in direction depends on the medium the wave travels out of and the medium the wave travels into Keep in mind that when we are talking about refraction, we are talking about a wave crossing a boundary

REFRACTION OF WAVES Most of our discussions of refraction will be about light ALL WAVES UNDERGO REFRACTION, but we are going to examine refraction of light as it is easier to demonstrate and see

REFRACTIVE INDEX Light travels fastest in a vacuum 3.00*10 8 m/s This speed gets the symbol ‘c’ in physics Light is slower in all other mediums The ratio of the speed of light in a vacuum to the speed of light in another medium is called the refractive index The refractive index gets the symbol n

ANGLE OF REFRACTION As light enters the new medium, the Normal still exists Just as in reflection The angle of refraction is the angle between the normal and the refracted ray

ANGLE OF REFRACTION The angle of refraction depends on the material If the wave moves into a material with a higher refractive index: n 1 < n 2 The velocity slows down The wave turns toward the normal The angle of refraction is smaller than the angle of incidence

ANGLE OF REFRACTION If the wave moves into a medium with a lower refractive index n 1 > n 2 The wave speeds up The wave turns away from the normal The angle of refraction is greater than the angle of incidence

SNELL’S LAW