1. Chapter 16
Waves motion

2. What is a wave?
A wave is defined as a Propagation of a disturbance through a medium
Wave flees the place of its creation, while water
[particle] does not.
A wave is a means of transferring energy from
one place to another.
Waves are closely related to oscillations.

3. Can you think of some examples of waves?

4. Waves
Sound
Light
Water
Radio
Seismic.

5. TYPES OF WAVES
Waves are classified into different types according to their natures :

6. Wave Types Mechanical Electromagnetic
e.g. Water waves, waves on a rope, sound
e.g. Radio, X-Rays, Light
Must have a substance to travel through
Cannot travel in a vacuum
Does not need a substance to travel through but can travel through various substances
Can travel in a vacuum
Vibrations passed on from molecule to molecule
Travel at very fast speed in a vacuum: 3 × 108 m/s

7. Traveling waves Transverse waves: Transverse waves:
The particles of the disturbed medium move perpendicular to the wave motion.
particle
wave

8. Traveling waves Longitudinal waves: Longitudinal waves:
The particles of the disturbed medium move parallel to the wave motion
Longitudinal waves:

9. Traveling waves Waves are closely related to oscillations
We’ll mainly deal with sinusoidal waves.

10. Basic Variables of Wave Motion
Terminology to describe waves
Crest: “Highest point” of a wave. Trough: “lowest point” of a wave.
Wavelength l: Distance from one crest to the next crest.
Wavelength l: Distance between two identical points on a wave.
Period T: Time between the arrival of two adjacent waves.
Frequency f: 1/T, number of crest that pass a given point per unit time
Amplitude A: the maximum position of a particle

11. Sinusoidal waves Brown curve: Snap shot at time t = 0 Blue curve:
Snap shot at later time.

12. Sinusoidal waves
The function describing a traveling sinusoidal wave:

13. Traveling sinusoidal wave
Black board example 17.1
Traveling sinusoidal wave
A sinusoidal wave traveling in the positive x-direction has an amplitude of 15.0 cm, a wavelength of 40.0 cm, and a frequency of 8.00 Hz.
Find the wave number k, the period T, the angular frequency w and propagation speed v of the wave.
If the vertical displacement of the medium at t = 0 and x = 0 is also 15.0 cm, what is the phase constant F?
Write a general expression for the wave function.