2. Wave Types
Transverse wave
• The motion of the medium is at right angles to
the direction the wave is moving. Particles of
the medium move up and down, but not
horizontally.
3. Wave Types
Longitudinal wave
• The motion of the medium is parallel to the
direction the wave is moving. Particles of the
medium move horizontally, but not up and down.
4. Wave
Characteristics:
Amplitude - (wave height)
• The maximum distance molecules are
displaced from their rest position.
• Amplitude indicates the energy of the wave.
5. Wave Characteristics:
Wavelength • The distance between two consecutive crests of a wave.
• Symbol for wavelength is the Greek letter lambda - λ
7. Wave Characteristics:
Wave speed • Wave speed depends on the medium in
which it travels.
• In a given medium, the speed of a wave is
constant.
Wave speed is calculated by the equation:
Speed = (frequency) (wavelength)
9. Sound:
• Longitudinal waves composed of a
series of compressions and
rarefactions.
• Mechanical – they must travel
through a medium.
• Sound waves cannot travel in the
vacuum of space because there is
no medium to transmit these
mechanical waves.
10. Properties of Sound
Intensity •
•
The amount of energy in a wave.
Intensity determines the amplitude of a wave.
•
•
Intensity relates to the loudness of a sound - the
greater the intensity, the louder the sound.
Decibels - the units of intensity.
•
Sounds over 120 decibels will cause pain in the ears.
•
Ear damage can begin with exposure to sounds as
low as 85 decibels.
11. Properties of Sound
Pitch •
•
•
•
•
•
•
How low or high the sound is.
The frequency of a wave determines its pitch.
Pitch is related to frequency - the higher the
frequency, the higher the pitch.
The human ear can hear sounds ranging from
20 Hz to 20,000 Hz.
Sounds over 20,000 Hz are called ultrasonic.
Thunder has a low pitch with a frequency less
than 50 Hz.
A whistle has a high pitch with a frequency
close to 1000 Hz.
12.
13. Light:
• Visible light is the
portion of the electromagnetic
spectrum that we can see.
• As the full spectrum of visible light
travels through a prism, the
wavelengths separate into the colors
of the rainbow because each color is a
different wavelength.
14. Light:
COLOR AND TEMPERATURE
• As objects grow hotter, they radiate
energy dominated by shorter
wavelengths.
• The color of stars tells scientists
about their
temperature.
15. Light:
COLOR AND
TEMPERATURE
• Our Sun produces more yellow light
than any other color because its
surface temperature is 5,500°C.
• The star Betelgeuse is cooler—about
3,000°C—and looks reddish.
• The star Rigel is hotter—about
12,000°C—and looks blue.
16. Radio
Waves
• Radio waves have the longest
wavelengths in the
electromagnetic (EM)
spectrum.
• They range from the length of
a football to larger than our
planet.
17. Radio Waves:
Radio Emissions in the Solar
System
• Astronomical objects that
have a changing magnetic field
can produce radio waves.
• Radio telescopes look toward
the heavens to view planets,
comets, giant clouds of gas
and dust, stars, and galaxies.
18. Radio Waves:
Radio Emissions in the Solar
System
• By studying the radio waves
originating from these sources,
astronomers can learn about their
composition, structure, and motion.
