refraction -refraction of sound -refraction of light
Post on 19-Jan-2016
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Refraction
-Refraction of Sound
-Refraction of Light
• Is it harder to push a lawn-mower on concrete or grass?
• Is it harder to walk through a pool full of water or air?
• Do you think that light waves also have a harder time going through water than air?
Refraction
Refraction• The change in direction of a wave as it
crosses the boundary between two media in which the wave travels at different speeds.
• Both light and sound waves change direction when they enter new media at angles greater than 0o.
Refraction of Sound• Sound waves are refracted when parts of a wave
front travel at different speeds.
• Do sound waves travel faster in warmer or colder air?
Refraction of Sound
Refraction of Light
Refraction of Light
• Light changes speed as it passes from one medium to another. This changes the directions of light rays.
Refraction of Light
• When light rays enter a medium in which their speed decreases, the rays bend toward the normal.
• When light rays enter a medium in which their speed increases, the rays bend away from the normal.
Index of Refraction and Snell’s Law
• Index of Refraction:
• Snell’s Law:
n = speed of light in vacuumspeed of light in material
n sin = n’ sin ‘
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