Transcript Refraction -Refraction of Sound -Refraction of Light Refraction • Is it harder to push a lawn-mower on concrete or grass? • Is it harder to.

Refraction
-Refraction of Sound
-Refraction of Light
Refraction
• 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
• 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:
n = speed of light in vacuum
speed of light in material
• Snell’s Law:
n sin = n’ sin ‘