Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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Waves
• 2 types of waves
– Mechanical
• Use matter to transfer energy through a medium
– Electromagnetic
• Do not need matter to transfer energy
Mechanical Waves
• Waves that REQUIRE a medium for the
energy to travel
Examples: water waves, sound waves,
energy moving through a slinky. What
else?
Mechanical Waves
• Use matter (Medium)
to transfer energy.
• The energy is
transferred from
particle to particle.
• SOUND IS A
MECHANICLE WAVE
There Are Two Basic Types of
Mechanical Waves.
Transverse Waves
• The energy traveling
through the wave causes
the particles to move at a
right angle to the
direction of the energy.
• This is what we usually
draw when representing
waves.
• Ripples on a pond are an
example of these.
The Second type of Mechanical
Wave
Compressional Waves
• In this type the
particles move in the
same direction as the
energy.
• Sound is a
Compressional Wave
Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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Wave Properties
• Amplitude
• Wavelength
• Frequency
• Human perception of amplitude –
loudness
• Human perception of frequency – pitch
Transverse Waves
• Crest – very top of wave
• Trough – very bottom of wave
• Amplitude – Distance between resting position and
crest/trough
• Wavelength – Distance from the top of one crest to the
next crest
• Frequency – Number of wavelengths to pass by a given
point in 1 second
– 2.5 in picture at right
Transverse Wave Examples
Transverse Waves (cont.)
• Frequency and Pitch
– As frequency increases pitch gets higher
– As frequency decreases pitch gets lower
Transverse Waves (cont.)
• Frequency and Wavelength
– As frequency increases wavelength decreases
– As frequency decreases wavelength increases
Compressional Waves
• Medium travels slightly
back and forth in the
same direction as the
energy is moving
Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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Electromagnetic Waves
• Waves that DO NOT require a medium for
the energy to travel
• Examples: Light, radio waves, x-rays,
gamma rays, etc. All waves on the
electromagnetic spectrum
Electromagnetic Waves
• These waves do not
need matter to travel
• Difference between
the different waves is
wavelength
• EM spectrum
illustrates the
differences
Electromagnetic Waves (cont.)
• Radio – listen to your
favorite station
• Microwaves – call your
friends
• Infrared – night vision
• Visible – you can see this
presentation
• Ultraviolet – tanning
• X-ray – see broken bones
• Gamma – kill cancerous
cells
Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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Sound
• Sound is a mechanical wave (requires a
medium to travel) and a compressional
wave (molecules colliding)
• The medium sound travels through are
molecules when they collide
Sound
• Sound is produced when an object vibrates.
• When an object vibrates it exerts a force on the
surrounding air
• Loudness of a sound is recorded in decibels
• As a sound gets louder, the amplitude of the wave
increases
Sound
• The moving air mass
carries the sound of the
vibration to your ear.
• The air is the MEDIA that
it travels through.
• Medium is what the wave
travels through (ex. solid,
liquid, gas)
• NO MEDIUM NO
SOUND!!!!
The Echo
• An echo is when a sound wave hits a hard
surface and bounces back, causing you to
hear the sound a second time
• Sonar uses echoes. It is a measure of
how long it takes the echo to return to the
source of the sound. Sonar can tell you
how far an object is from you.
Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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Speed of Sound
• The speed of sound is different depending
on the medium it travels through
Speed of Sound
• Sound travels at
different speeds
through different
medium
• The more dense a
material the faster
sound travels
– 346 m/s in warm air
– 5,000 m/s in aluminum
– 3,240 m/s in gold
Speed of Sound
• Sound travels better through high-density
materials
– The closer the molecules are together, the faster they
can collide and transfer energy
Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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Light
• Properties of Light
Light
• EM wave that travels transversely (up and
down motion)
• Primary colors are red, green and blue
• White light is made up of all colors
• Black is the absence of color
Light (cont.)
• We see colors because objects reflect light
• If you see a color, that specific color is
being reflected while the rest are being
absorbed (taken in) by the medium
• White reflects all colors
• Black absorbs all colors
What is Light?
• It is a transverse wave that carries energy
• It is a small part of the ElectroMagnetic
Spectrum
• Because it is part of the electromagnetic
spectrum, it can travel through a vacuum
(space)
How do you see the things around
you?
Without light, there is no sight!
Light REFLECTS off of objects.
How we see
• When light strikes an object the light
bounces off of the object and then into our
eye.
• For example, the light from the this
projector hits the screen and then is
reflected to your eye.
Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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Transparent, Translucent, Opaque
Opaque, Translucent, Transparent
• Objects that do not let light pass through
them are opaque. Ex. Walls, your desk,
the science book
• Objects that let light pass clearly through
them are transparent. Ex. Windows,
plastic wrap, eye glass lenses
• Objects that let only some light pass
through are translucent. Ex. waxed paper,
frosted glass
Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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Color
COLORS
• The suns light might appear white, but it is
a mixture of colors.
• White light is produced when you mix the
colors of the rainbow together.
Light Color Mixing
• The primary colors of light are RED, BLUE
and GREEN
So why do we see different colors?
• When white light hits an object some of it
may be absorbed by the object while the
rest of the light is reflected. The colors we
see are the reflected colors.
Waves, Sound, and Light MENU
Mechanical Waves
Electromagnetic Waves
Light
Wave Properties
Color
Sound
Transparent, Translucent, Opaque
Speed of Sound
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