1. Types of Wave Describing Waves The Wave Equation
Mechanical Waves
Types of Wave
Describing Waves
The Wave Equation

2. The Nature of Waves

3. What is a wave? A disturbance That propagates through space and time
And transfers energy
a.k.a. progressive wave or traveling wave

4. Disturbance dropping a stone in the water plucking a guitar string
blowing through a pipe
Disturbance

5. An Unusual Disturbance

6. Types of Wave Mechanical Waves Produced by a disturbance
Transmitted by particles of the medium vibrating to and fro

7. Water (liquid)
String (solid)
Air (gas)
Medium

8. Transverse Waves
direction of disturbance is perpendicular to the direction of travel of the wave
Examples:
String instruments
Earthquake s-waves
Light

9. Diagram of a transverse wave
crest
trough
Equilibrium position

10. Longitudinal Waves
direction of disturbance is parallel to the direction of travel of the wave
Examples:
Sound waves
Ultrasound
Earthquake p-waves

11. Diagram of a longitudinal wave
compression
rarefaction

12. Wavelength Amplitude Period Frequency Speed
Describing Waves
Wavelength
Amplitude
Period
Frequency
Speed

13. Describing Waves period wavelength displacement amplitude position
time

14. Wavelength
Equivalent to one complete vibration
Distance from crest to crest, or trough to trough, OR
Distance from two identical successive points on a graph
Unit: meter, m
Symbol: lambda, λ

15. Amplitude
Maximum displacement of vibrating particles
Unit: meter, m
Symbol: A

16. Period
Time for one complete vibration
Time corresponding to one wavelength
Unit: second, s
Symbol: T

17. Frequency
Number of vibrations in one second
Reciprocal of period, 1/T
Units:
vibrations per second, s-1
cycles per second, s-1
Hertz, Hz
Symbol: ƒ

18. Wave Speed Distance moved by any point on the wave in one second
Product of wavelength and frequency
Units: ms-1
Symbol: v

19. What is the amplitude in metres and the wavelength in metres?
Displacement (m)
Distance (m)
0.5
-0.5

20. What is the speed of this wave?
For the same wave, what is the period in seconds and the frequency in Hertz?
Displacement (m)
Time (s)
0.2
0.4
0.6
0.8
1.0
0.5
-0.5
What is the speed of this wave?

21. What is the time period and frequency of this wave?
20 ms
What is the time period and frequency of this wave?

22. A water wave travels through a pond with a speed of 1ms-1 and a frequency of 5Hz. What is the wavelength of the waves?
The speed of sound is 330ms-1 (in air). When Ricky hears this sound his ear vibrates 660 times a second. What was the wavelength of the sound?
Purple light has a wavelength of around 6x10-7m. If its frequency is 5x1014 Hz what is the speed of light?
Red light travels at the same speed. Work out its frequency if its wavelength is 4x10-7m.