Waves
Waves
A wave is a disturbance that carries
energy through matter or space.
It does not move matter.
Energy may spread out as a wave
travels.
Types of Waves
Mechanical Waves – waves that require a
medium
A medium is a material that the wave moves
through.
Stone thrown in a pond
Sound from a stereo
Earthquake
Types of Waves
Electromagnetic Waves – waves that do
not require a medium
Light through space
Radio waves
Radar
Transverse & Longitudinal
Waves
Transverse waves – waves in which the
motion of the particles is perpendicular to the
motion of the wave.
Waves in a rope
Longitudinal waves – waves in which the
motion of particles is parallel to the direction
of the wave
Sound waves
Simulation
Characteristics of Waves
Wavelength – the distance between two
similar points on a wave
Characteristics of Waves
Amplitude – measured the amount of
particle vibration or the height of the
wave – half the height of the wave.
Characteristics of Waves
Frequency – measures the rate of vibrations
As frequency increases the wavelength decreases.
Electromagnetic Spectrum
The electromagnetic spectrum shows all
the different types of electromagnetic
waves (transverse).
The higher the frequency, the more
energy it has.
They all travel at the speed of light.
Electromagnetic Spectrum
Wave Speed
The speed of a wave depends on the material it is
passing through.
The denser the material, the faster a mechanical
wave will move through it (sound travels 3 – 4 times
faster through water than air)
Example: Door, Train Tracks
A dense material will slow down an electromagnetic
wave (light travels slower through glass than air)
Wave Speed
Mechanical waves travel fastest through
solids and slowest through gasses.
Transverse waves travel fastest through
gasses and slowest through solids.
Doppler Effect
The Doppler effect is a change in the
observed frequency of a wave resulting from
the motion of the source or observer
Waves are compressed as the sound source
comes toward you producing a higher pitched
sound. When it travels away the waves are
farther apart producing a lower pitched sound
This occurs in both sound and light.
Doppler Applet
Characteristics of Waves
Higher the frequency the greater the energy.
Lower the frequency the lower the energy.
Human hearing:
Dog hearing:
20 Hz to 20,000 Hz
40 Hz to 46,000 Hz