Transcript III. Wave Properties of Light

Ch. 19 - Light
III. Wave Properties of Light
(p.546-550)
 Reflection
 Refraction
 Diffraction
 Interference
A. Reflection
Normal
Reflection
when a wave
strikes an object
and bounces off
incident beam
reflected beam
A. Reflection
Law of Reflection
the angle of
incidence equals
the angle of
reflection
B. Refraction
Refraction
bending of waves when passing
from one medium to another
caused by a change in speed
• slower (more dense)  light
bends toward the normal
• faster (less dense)  light
bends away from the normal
SLOWER
FASTER
B. Refraction
Refraction depends on…
speed of light in
the medium
wavelength of
the light - shorter
wavelengths (blue)
bend more
B. Refraction
Example:
View explanation.
C. Diffraction
Diffraction
bending of waves
around a barrier
longer wavelengths
(red) bend more opposite of refraction
D. Interference
Interference
constructive  brighter light
destructive  dimmer light
E. Cool Applications!
Fiber Optics
Total Internal Reflection
• when all light is reflected back
into the denser medium
E. Cool Applications!
The “Broken Pencil”
refraction
View animation and explanation of the “Broken Pencil.”
E. Cool Applications!
Rainbows
refraction-reflection-refraction
E. Cool Applications!
Diffraction Gratings
glass or plastic made up
of many tiny parallel slits
may also be reflective
spectroscopes, reflective
rainbow stickers, CD
surfaces
E. Cool Applications!
Thin Films - Bubbles & Oil Slicks
interference results from double reflection
E. Cool Applications!
Blue Sky & Red Sunsets
• Molecules in atmosphere
scatter light rays.
• Shorter wavelengths (blue, violet)
are scattered more easily.
SUNSET
• more atmosphere
• more scattering
• orange-red sky & sun
NOON
• less atmosphere
• less scattering
• blue sky, yellow sun