1. General Wave Properties

2. General Wave Properties
describe what is meant by wave motion as illustrated by vibration in ropes, springs and experiments using a ripple tank
state what is meant by the term wavefront
show understanding that waves transfer energy without transferring matter
define speed, frequency, wavelength, period and amplitude
recall and apply the relationship velocity = frequency x wavelength to new situations or to solve related problems
compare transverse and longitudinal waves and give suitable examples of each

3. Wave Wave is the product of a vibration
Two types of wave: transverse and longitudinal

4. Wave
During wave motion, particles vibrate about their fixed position and the waveform progresses (travels).
Transverse waves: particles vibrate perpendicular to wave motion eg. Light wave, water ripple
Longitudinal waves: particles vibrate parallel to wave motion eg sound wave.

5. Wave (Transverse Wave)
wavelength
crest
crest
amplitude
trough
wavelength

6. Wave (Longitudinal Wave)
wavelength
wavelength
rarefaction
compression
Compression: region of high pressure
Rarefaction:
Region of low pressure
distance
pressure
compression
compression
rarefaction
rarefaction

7. Wave Frequency, f – number of oscillations per second <Hz>
Period, T – time taken for one oscillation <s>
Wavelength,  – distance between two consecutive particles in phase. <m>

8. Waves
Example
The diagram below shows a transverse wave moving to the right.
a)In which direction will the particle T and V move?
b) Which particle is in phase with T? W Q R U S V X T Y

9. Wave (cont’d) W Q R U S V X T Y
Particle T moves upwards; V moves downwards.
Particle X is in phase (in step) with particle T.

10. Wave Relationship between frequency, f and period, T
SI unit for frequncy, f: Hz
SI unit for period, T: s

11. Wave
Relationship between wave speed, v; frequency, f and wavelength, 
SI unit for speed, v: ms-1
v = f 

12. Wave
Example
Transverse waves are produced in a long rope by moving one end from side to side. The frequency of the wave is 2Hz.
a) What do you mean by 2Hz?
b) What is the wavelength if the speed of the wave is 0.5ms-1?

13. Wave a) What do you mean by 2Hz?
Each particle on the rope oscillates 2 cycles per second
b) What is the wavelength if the speed of the wave is 0.5ms-1?
v = f x 
0.5 = 2 x 
 = 0.5/2
= 0.25m

14. Wave
The speed of the wave motion, v is related to its frequency, f and wavelength  through the equation:
The frequency of the wave is related to the period of vibration, T through:
v = f 
f T = 1

15. Wave Distance/m displacement/m 2 4 6 Wavelength, = 4m v = f x 2 4 6
Wavelength, = 4m
v = f x 
= 0.5 x 4
= 2ms-1
time/s
displacement/m 1 2 3
Period, T = 2s
Frequency, f = 0.5Hz

16. Wave
The displacement time graph of a transverse wave is shown in the figure below. Its wavelength is 3m.
Calculate
the speed of the wave
the time taken for the wave to travel a distance of 3000km
Disp/ 10-5m
0.3
0.7
1.2
time/10-5ms
1.7
2.2
2.7

17. Wave a) v = f  = [1/(1 x 10-5 x 10-3) ]x 3 = 3 x 108 ms-1
Disp/ 10-5m
0.3
0.7
1.2
time/10-5ms
1.7
2.2
2.7
a) v = f 
= [1/(1 x 10-5 x 10-3) ]x 3
= 3 x 108 ms-1
b) t = 3000 x 1000 / 3 x 108
= 100 s
T = ( ) 10-5ms
= 1 x 10-5 x 10-3 s

18. Wave What is a wavefront?
Source:http//
What is a wavefront?
Wavefront is a line that joins all the points (usually the crests) on the wave that are in phase
Wavefront is likened to the bird’s eye view of a wave.
Changes in wavefront indicates changes in speed of wave or presence of underwater features

19. wavelength
direction

20. Waves Frequency d Medium (density / depth etc) Speed1 2 3
As the wave approaches a shallower region, the speed of the wave reduces due to larger resistive forces .
Frequency d
Medium (density / depth etc)
Speed
Source of vibration

21. This is due to the shallower sea bed near the beach
Smaller wavefronts as the wave approaches shows the decrease in speed of the wave.
This is due to the shallower sea bed near the beach
Source//

22. Wave bends towards normal
large wavelength
Understanding refraction
water
glass
Wave bends towards normal
short wavelength
Wave slows down when entering denser medium, experiencing higher resistance

23. Conclusion Wave motion is the result of vibrations.
There are two types of waves: transverse and longitudinal.
Wave travels as the particles vibrate about their fixed positions.
Relationship v = f x  us to determine the speed of wave.
The wavefront tells us direction of travel and their distance between tells us the wavelength.
Changes in wavefront gives us an indication of changes in wave medium.