Transcript Behavior of Light Waves

Behavior of Light Waves
S8P4.b
• Describe how the behavior of light waves
is manipulated causing reflection,
refraction, diffraction, and absorption
Manipulate
to affect or control
What’s It Mean?
o Light waves change when they hit
materials.
o The way light waves change depends on
the material the waves hit.
o Describe how changes in light waves
cause reflection, refraction, diffraction, and
absorption.
Getting the Idea
• Waves do not always travel in one
direction; they often bounce off
one surface and then travel in
another direction.
• Waves can continue to change
direction long after the original
source of the energy has stopped.
• When sound waves demonstrate this
property, you hear echoes.
• Light waves can also bounce off surfaces
and change the direction in which they
travel.
• When any type of wave hits and
obstacle or passes from one medium to
another, it is possible that the wave will
change in speed, direction, or shape.
Reflection
• Occurs when a wave bounces back after striking a
barrier.
• Examples of barriers include mirrors and shiny
pieces of metal.
• Water waves, light waves, sound waves, and heat
all can be reflected.
• An echo is a reflected sound wave.
• Reflection is the property of light that allows you to
see yourself in a mirror.
Law of Reflection
• States that the angle of incidence is equal
to the angle of reflection.
Absorption of Light
• A beam of light becomes dimmer partially
because of absorption and scattering.
•Absorption is the transfer of energy to
particles of matter.
• When you shine a flashlight in the air, the
air particles absorb some of the energy
form the light. This causes the light to
become dim.
•The farther the light
travels from the flashlight,
the more it is absorbed by
air particles.
Scattering of Light
• The releases of light energy by particles of
matter that have absorbed energy.
• When the light is released, it scatters in all
directions.
• Light from a flashlight is scattered out by air
particles. The scattered light allows you to see
objects outside the beam. However, because
light is scattered out from the beam, the beam
becomes dimmer.
Why is our sky blue?
• The gases and other particles that make
up our atmosphere scatter the color blue
more than the other six colors.
Refraction
• The bending of a wave as it passes at an
angle from one medium to another.
A hands lens makes objects appear
larger because of refraction.
Refraction
• The bending of a wave as it passes at an
angle from one medium to another.
• Refraction of light takes place when light
passes from one medium having one
density to a medium with a different
density.
• The refraction of light occurs because the
speed of light varies depending on the
material that it passes.
Light travels more
slowly through the
glass and water than it
does air. Therefore, it
refracts as it passes at
an angle from air to
glass, to water or from
water, to glass, to air.
Optical Illusions
• Stare at the four dots in the center of this
page for about 30 seconds. Try not to
blink. Then lean back, look at the ceiling
and blink your eyes a few times. Did you
see Jesus?
•
Refraction and Color Separation
White light
can bewhite light is refracted, it separates
•When
separated
into
different colors.
into
•Color
separation during refraction is
different
responsible
colors (Royfor the formation of rainbows.
G. Biv) by
refraction.
What causes a rainbow?
• Rainbows are created when sunlight is
refracted by water droplets in the
atmosphere.
Diffraction
• refers to the bending, spreading, and
interferences of waves when they go through a
narrow opening.
•Occurs with any type of wave.
•A wave is diffracted more when its wavelength
is similar in size to the barrier or opening.
Transmission
• The passing of waves through a medium.
• Example: A radio wave (electromagnetic
wave) is produced at the radio station.
The wave travels from the radio station’s
transmitter out in all directions at the
speed of light. Your radio detects the EM