2. 9.2 Waves
• A wave is an oscillation that travels from one
place to another.
• If you poke a floating ball, it oscillates up and
down.
• The oscillation spreads outward from where it
started making a wave
3. 9.2 Waves
• A disturbance has to create a wave. When you
drop a ball into water, some of the water is
pushed aside and raised by the ball. The ball
doesn’t travel with the wave, the energy of the
wave just passes through!
4. 9.2 Waves
• Waves are a traveling
form of energy
because they can
change motion.
• Waves also carry
information, such as
sound, pictures, or
even numbers.
5. Did you know?
• All of the information that you receive
in your __________ and _________
comes from waves!!!
6. 9.2 Frequency, amplitude, and
wavelength
• You can think of a wave as a moving series of
high points and low points.
• A crest is the high point of the wave.
• A trough is the low point of a wave.
7. 9.2 Frequency, amplitude, and
wavelength
• Wavelength is the distance from any point on
a wave to the same point on the next cycle of
the wave.
• The distance between one crest and the next
crest is a wavelength.
8. 9.2 Frequency, amplitude, and
wavelength
• The amplitude is the maximum amount the
wave moves away from equilibrium.
• Equilibrium is the average or resting position
10. Which type of wave is the
fastest, water, light or sound?
•
Water: couple of miles per hour
•
Light: 670,616,629 miles per hour
(186,282 miles/second!!!)
• Sound: 660 miles per hour
11. 9.2 Transverse waves
• The oscillations of a transverse wave are
not in the direction the wave moves.
12.
13. 9.2 Longitudinal waves
• Longitudinal waves do oscillate in the
same direction that the wave travels
(Spring hooked to the wall)
14.
15.
16.
17. 9.2 The speed of waves
• The speed of a water wave is how fast the
wave spreads, NOT how fast the water surface
moves up and down or how fast the dropped
ball moves in the water.
How do we measure the wave speed?
18. 9.2 The speed of
waves
• A wave moves one
wavelength in each
cycle.
• Since a cycle takes one
period, the speed of
the wave is the
wavelength divided by
the period.
19. 9.2 The speed of waves
• The speed is the distance traveled (one
wavelength) divided by the time it takes
(one period).
• We usually calculate the speed of a wave
by multiplying wavelength by frequency.
20. Formulas for Wave Speed
• Speed = frequency x wavelength
• Speed = wavelength / period
**Wavelength is measured in meters,
frequency is measured in hertz, period
is measured in seconds, speed is
measured in m/s.
21. 9.2 When a wave encounters
objects
• When a wave hits an object or a surface
called a boundary, four things can
happen.
22. 9.2 Reflection
• When a wave bounces off an object we call it
reflection.
• A reflected wave is like the original wave but
moving in a new direction.
23. 9.2 Refraction
• Refraction occurs when a wave bends as it
crosses a boundary.
• We say the wave is refracted as it passes
through the boundary.
