ANSWER:
• Water waves in the ocean.
• Microwaves in the microwave oven.
• Light waves from the sun.
• Radio waves transmitted to the radio.
• Sound waves from the radio and voices in
the phone.
Unit 2: Waves.
A wave: is a disturbance that transmits
energy through space or matter.
Unit 2: Waves.
- Mechanical waves transfer energy by the vibration of
particles in a medium.
- Sound waves require a medium.
- If there are no particles to vibrate, no sound is
possible! For example, if you put in alarm clock in a jar
and remove all the air to create a vacuum, you will
not be able to hear the alarm!
See text pgs.510-517
Unit 2: Waves.
-Medium: a substance through
which a wave can travel
A medium can be a: solid, liquid,
or gas.
The plural of medium is media.
Unit 2: Waves.
Waves carry energy, but DO NOT carry matter.
For example, sound travels through air, but the air
does not travel with the sound. If it did, you would
feel a rush of air every time you listened to music.
Unit 2: Waves.
So what does an
explosion in
space sound like?
Nothing- because there is no medium
in space!
Unit 2: Waves.
-Waves that do not need a medium are called
electromagnetic waves.
- Visible light, microwaves, tv and radio signals,
and X rays do not require a medium!
Unit 2: Waves.
There are TWO main types of waves:
Transverse
Longitudinal
Unit 2: Waves. Transverse Waves.
Waves in which the particles vibrate with an up-anddown are transverse waves.
The particles move perpendicular to the direction that
the wave is traveling
If the wave travels left/right, then it causes up/down
vibrations.
See text p.513
Unit 2: Waves. Transverse Wave.
Parts of a transverse wave
Unit 2: Waves. Transverse Wave.
Parts of a transverse wave
Crest: The highest point of a transverse wave
Trough: The lowest point between each crest
Example:
LIGHT energy
Unit 2: Waves.
Longitudinal or Compression Wave: the
particles of the medium vibrate back and forth
along the path that the wave travels.
See text p.514
Unit 2: Waves.
Parts of a longitudinal wave
Unit 2: Waves.
Compression: a section of a longitudinal wave where
the particles are crowded together
Rarefaction: a section where the particles are less
crowded than normal
Example:
SOUND energy
See text p.514
Unit 2: Waves.
Amplitude
Amplitude is the
maximum distance a
wave vibrates from its
rest position.
Low amplitude
=
Low energy
High amplitude
=
high energy
Unit 2: Waves.
Wavelength
On a transverse wave, measure from one crest to the
next crest, OR one trough to the next trough.
On a longitudinal wave, measure from one
compression to the next compression, OR one
rarefaction to the next rarefaction.
Unit 2: Waves.
Frequency
Frequency: the number of waves produced in a given
amount of time. Measured in Hertz.
1 hertz (Hz) = 1 wave per second.
5 hertz (Hz) = 5 waves per second.
Higher frequency
=
More energy