# Waves, Light, Sound and Color

```Waves, Light, Sound and
Color
Waves
Transfer energy through
matter or space
Waves
May be longitudinal
Or transverse
Waves
Waves travel through a medium
such as:
water
air
solids
Wave Properties
reflection
refraction
interference
Wave Properties
Diffraction: the
bending of a
wave around the
edge of a barrier.
Reflection, refraction, diffraction
and interference
Sound waves
 Longitudinal waves
 Need a medium to travel through
 Speed of sound is 340 m/s in air
Water waves
Water waves have transverse and longitudinal
characteristics.
Energy is transferred, but the particles stay essentially
in the same place
Light: particle or wave?
Light particles are called photons
Light: Particle or wave?
 BOTH!!
 Light does not need a medium to travel
through.
Doppler effect
 Change in frequency and pitch of a
sound.
 Due to the motion of either the sound
source or the observer.
 Listen!
Doppler effect of sound
Doppler effect in light
 As stars move away from earth,
there is a shift in the light towards
the red end of the spectrum.
Color
• When light strikes a surface, it can
be transmitted, absorbed, or
reflected
Transmission of light
• When light is transmitted, a
substance is said to be transparent.
• The color that is transmitted is the
Transparent objects
transmit color
• Red glass absorbs all colors of light
except red, which it transmits.
Absorption of light
Reflection and
absorption of light
• Opaque objects reflect and absorb
light.
• The color of an opaque object is the
color it reflects.
Opaque objects reflect
and absorb light
• This apple reflects red and
absorbs all other colors.
Translucent objects
transmit some light
Color
• Primary colors are red, green
and blue.
• Primary colors may be combined
to make white light.
Complimentary colors
• 2 colors that combine to form white
light.
Primary colors of light together form white light. But
primary pigments together make black.
This is because they absorb all colors.
Bye-bye!
```