I can describe waves
and their parts.
Warm Up 5/17
List as many types of waves as you can think of.
Waves
Waves
A wave is a disturbance that transfers energy
through matter or space.
The material a wave travels through is called
the medium.
Waves
Waves can be divided into mechanical and
electromagnetic waves.
Mechanical Waves require a medium to pass
through. Ex: sound, ocean waves
Electromagnetic waves are fluctuations in
electric and magnetic fields and do not require
a medium. Ex: radio, light, x-rays
Waves
The medium may be temporarily displaced as
the wave passes but it is not carried with the
wave.
The wave only carries the energy.
Transverse Waves
Transverse waves displace the medium at right
angles to the direction the wave is traveling.
Longitudinal Waves
Longitudinal (compression) Waves - displace
the medium parallel to the direction the wave is
moving; “push-pull” waves.
Parts of a Transverse Wave
Trough – the lowest point of the wave
Parts of a Transverse Wave
Wavelength(λ) – the distance from crest to crest
or trough to trough
Parts of a Transverse Wave
Crest – the highest point of the wave
Parts of a Transverse Wave
Amplitude - How far the medium is displaced
by the wave; the distance from center to crest.
Parts of a Longitudinal Wave
Compression – where the medium is closest
together, most dense.
Parts of a Longitudinal Wave
Rarefaction – where the medium is the most
spread apart, least dense.
Parts of a Longitudinal Wave
Wavelength (λ) - the distance from
compression to compression, or rarefaction to
rarefaction.
Parts of a Longitudinal Wave
Amplitude – How far the medium is displaced;
how much the medium is compressed or
stretched.
Frequency
Frequency(f) is the number of wavelengths that
pass a point in one second.
Frequency is measured in cycles/second or
hertz(Hz).
Frequency
Wave Energy
A frequency of 10 Hz means ten crests will pass
in one second.
The amount of energy the wave carries affects
its amplitude and frequency.
A frequency of 10 kHz means 10,000 crests will
pass in one second.
The greater the amplitude, the greater the
energy of the wave.
For electromagnetic (light) waves higher
frequency means more energy.
Wave Speed
The speed a wave travels at depends on its
medium.
Wave Speed
If the speed of a wave does not change…
velocity (of a wave) = frequency • wavelength
Increasing the frequency will ________________
the wavelength.
This is not the speed of the medium; it is the
speed of the energy the wave is carrying.
Decreasing the frequency will
________________ the wavelength.
Wave speed
Wave Speed
As you watch an ocean wave created by a
passing boat you notice the crests are 5 meters
apart and they cause a buoy to bob up and down
1.5 times per second. How fast is the wave
traveling?
A seismic wave travels from the epicenter of an
earthquake and reaches a seismic measuring
station 10 km away in 2 seconds. The
seismograph measures a frequency of 0.05 Hz.
What is the wavelength of the wave?