Longitudinal and transverse waves

1. Waves

3. What are waves?
A wave is a phenomenon in which
energy is transferred through
vibration.

4. Types of Waves
Transverse Waves
Longitudinal Waves

5. Transverse Waves
are waves which travel in a
direction perpendicular to the
direction of vibrations.
Direction of vibrations
Direction of wave

6. Generating Transverse
Waves

7. Transverse Waves
examples include
water waves
rope waves
light wave
electromagnetic waves

8. Longitudinal Waves
are waves which travel in a direction
parallel to the direction of vibrations.
Direction of vibration
Direction of wave
examples include
sound wavessound waves

9. Generating of Longitudinal
Waves [slinky spring]

10. Characteristics of A Wave
Crests and Troughs
Amplitude
Wavelength
Frequency
Period
Speed

11. Crests and Trough
Crests are high point of a wave
Troughs are low point of a wave
displacement
distance
crest crest
troughtrough

12. Amplitude (A)
is the height of a crest or depth of a
trough measured from the normal
undisturbed positions.
displacement
distance
crest crest
trough
Amplitude
Amplitude

13. SI Unit For Amplitude
is measured in metres (m)
displacement
distance
crestcrest crestcrest
trough
Amplitude
Amplitude

14. Wavelength (l)
is the distance between two
successive crests or troughs
displacement
distance
Amplitude
AmplitudeAmplitude
crestcrest crest
trough trough
Wavelength
Wavelength

15. SI Unit For Wavelength
is measured in metres (m)
displacement
distance
Amplitude
Amplitude
crestt crest
trough trough
Wavelength

16. Frequency (f)
is the number of vibrations in one
second.

17. SI Unit For Frequency
is the Hertz (Hz)
1 Hz is 1 vibration in 1 second.
50 Hz is 50 vibrations in 1 second.

18. Test Yourselves
Explain the meaning of
 28 Hz,
 100 Hz ,
 135 Hz,
 1570 Hz.

19. Period (T)
is the time taken for one complete
vibration. (or oscillation or cycle)

20. SI Unit For Period
is measured in second (s)

21. Relationship between Period (T)
and Frequency (f)
f = 100 Hz Þ T = 1/100 s
f = 40 Hz Þ T = 1/40 s
f = 23 Hz Þ T = 1/23 s
f = 8 Hz Þ T = 1/8 s
f = f Hz Þ T = 1/f s

22. Relationship Between
f and T
f
1T=

23. Speed Of a Wave
is the distance moved in one second.

24. SI Unit For Speed
is measured in metre per second
(ms
-1
or m/s)

25. Wave Equation
Speed of a wave
= wavelength ¸ period
= wavelength x frequency
where v = speed, f = frequency and
l = wavelength
V = lf

26. Describing Waves
Displacement-Time Graph
for one particle on the wave
timetime
displacementdisplacement

27. GCE O-LevelGCE O-Level
Past Examination PaperPast Examination Paper
Science (Physics)

28. Nov 1991
9. The diagram shows the outline of a water wave.
What are the values of the amplitude and the
wavelength?
amplitude / cm wavelength / cm
A 0.6 10
B 0.6 20
C 0.6 30
D 1.2 20
B

29. GCE O Nov 1994
11. Which wave is longitudinal ?
A light
B radio
C sound
D water
C

30. D
O’ level Physics Nov 1995
11. The speed of 100 Hz wave was measured on four
different days. The results are shown in the table.
On which day the wave have the longest
wavelength ?
day speed of wave
A 315 ms
-1
B 320 ms
-1
C 335 ms
-1
D 340 ms
-1

31. GCE O Nov 1996
9. A source vibrates at frequency of 20 Hz and
produces waves of wavelength 0.02 m.
At which speed do these waves travel out from
the source ?
A 0.001 ms
-1

B 0.021 ms
-1

C 0.40 ms
-1

D 20 ms
-1

C
Hint:
v = lf

32. Nov 1998
9.A VHF radio station broadcasts at a frequency of
60MHz (6.0 x 10
7
Hz). The speed of radio
waves is 3.0 x 10
8
ms
-1
.
What is the wavelength of the waves broadcast by
the station?
A 0.2 m
B 0.5 m
C 2.0 m
D 5.0 m D
Hint:
v = lf

33. Nov 1998
5.The diagram shows a coil spring along which a
longitudinal wave is moving.
(a) Mark on the diagram a distance equal to the

wave length of the wave. [1]
(b) Label on the diagram with the letter C where
the coils of the spring are compressed. [1]
Wave length
C
(continue in next slide)
C C

34. (c) Is the wave on the spring more like a sound wave

or a light wave? [1]
Nov 1998
(Cont. …) Q 5
Sound wave, because sound wave is a longitudinal
wave but light wave is a transverse wave..

35. Nov 1997
5. The diagram below shows a transverse wave
travelling a rope.
(a) Mark on the diagram which is equal to (i)
the wavelength, (ii) the amplitude of the wave.
Label your answers. [2]
(b) If the wavelength is 0.8m and the frequency
is 2 Hz, what is the speed at which the wave
moves along the rope ? [2]
wavelength
amplitude
v = lf = 0.8 x 2 = 1.6 ms
-1

36. Nov 1996
6(a)Explain the difference between a transverse
and a longitudinal wave. [2]
(b)State one example of each type of wave.
Transverse
Longitudinal [2]
Light
Sound
Transverse wave is a wave that its direction of
vibration is perpendicular to the direction of
propagation. It can travel through vacuum.
Longitudinal wave is a wave that its direction of
vibration is parallel to the direction of
propagation. It needs medium to travel.

37. 9.(a)Explain the difference between transverse and
longitudinal waves, referring in your answer to
the direction in which the waves travel. [2]
GCE ‘O’ LEVEL Nov 1995
Transverse waves are waves that their direction
of vibration is perpendicular to their direction
of propagation.
Longitudinal waves are waves that their
direction of vibration is parallel to their
direction of propagation.
(continue on next slide)

38. 9.(b) The speed of sound in water is 1500m/s. What is a
wave length of a sound wave of frequency 250Hz
travelling through water ? [2]
Since v = lf
therefore 1500 = l 250
l = 1500 / 250 = 6.0 m
(Cont. …) Q. 9 Nov 1995

39. Nov 1993
6. The diagram shows the air pressure at different
distances from a loudspeaker.
(continue on next slide)
(a) Mark carefully on the diagram: [2]
(i) a distance which is the wavelength of the
sound wave;
(ii) the amplitude of the sound waves.
wavelength
amplitude

40. 6(b) If the wavelength of a sound wave of frequency
250 Hz is 1.4 m, calculate the speed of the wave.
[2]
(Cont. …) Q. 6 Nov 1993
since v = lf
therefore, = 1.4 x 250
= 350 ms
-1

41. 5.(a)With the aid of a diagram, explain what is meant
by the frequency and wavelength of a wave. [5]
GCE O Nov 1990
(b) What is a longitudinal wave ? [2]
l
Frequency is the
number of vibrations
per second.
Wavelength is the distance from a point on a
wave to its next corresponding point.
It usually denote as l..
Longitudinal wave is a wave that its direction
of vibration always parallel to the direction of
propagation.
(continue in next slide)