1) There are two main types of waves - transverse waves where the displacement is perpendicular to the direction of propagation like light waves, and longitudinal waves where displacement is parallel to propagation like sound waves. 2) Key wave properties are defined including wavelength, frequency, amplitude, and period. 3) Waves transfer energy and information through a medium without the medium moving significantly, such as light carrying energy from the sun and waves transferring energy in oceans.

1. Waves
Sound and Light
Cambridge IGCSE

2. Transverse waves
• Definition:
A wave in which the direction of displacement is
perpendicular to the direction of propagation, as
a surface wave of water.
Eg. Light

3. Longitudinal waves
• Definition
A wave in which the direction of displacement
is the same as the direction of propagation, as a
sound wave.
Eg. Sound

5. Definitions
• Wavelength (λ):
The distance, measured in the direction of
propagation of a wave, between two successive
points in the wave that are characterized by the
same phase of oscillation.
SI unit is the metre (m).

6. Definitions
• Frequency (F)
The number of cycles or completed alternations
per unit time of a wave or oscillation.
SI unit-hertz (Hz)

7. Definitions
• Amplitude (A)
The absolute value of the maximum
displacement from a zero value during one
period of an oscillation.
SI unit is the metre (m).
In transverse waves,
this is half the crest-to-trough height

8. Definitions
• Period (T):
This is the time taken for one point on the wave to
complete one oscillation. Or you can think of it as
the time taken to produce one complete wave.
The SI unit is second (s).
The distance the wave travel’s in 1 second
The speed is dependant on the substance or
medium in which the wave is passing through

9. the absolute value of the maximum
displacement from a zero value during one
period of an oscillation.

10. Waves transfer energy and
information
• You can feel the energy in infra-red waves
from the sun

11. Waves transfer energy and
information
• See the energy contained in the oceans waves

12. Waves transfer energy and
information
• See the information contained in the light
reaching your eyes

13. Waves transfer energy and
information
• Waves are vibrations that transfer energy
through a medium without causing the
individual particles of a medium to move
significantly from their equilibrium or position
of rest.

14. Formula
v = f x λ

15. Reflection
• Def: the waves will always reflect in such a
way that the angle at which they approach the
barrier equals the angle at which they reflect
off the barrier.

16. Refraction
• Def: waves involves a change in the direction
of waves as they pass from one medium to
another. Refraction, or the bending of the
path of the waves, is accompanied by a
change in speed and wavelength of the waves.

17. Diffraction
• Def: a change in direction of waves as they
pass through an opening or around a barrier
in their path. Water waves have the ability to
travel around corners, around obstacles and
through openings.

18. Wave interference
• Occurs when two waves meet while traveling
along the same medium.

19. Light
Def: The movement of light conceptualized
as a wave, defined by such properties as
reflection, refraction, and dispersion

20. Visible light is a form of electromagnetic (EM)
radiation, as are radio waves, infrared radiation,
ultraviolet radiation, X-rays and
microwaves. Generally, visible light is defined as
the wavelengths that are visible to most human
eyes.

21. • Light travels in a straight line
• Speed of light 299,792 kilometers per second
• Polarized light has vibrations confined to a
single plane that is perpendicular to the
direction of motion

22. • As light enters your eyes, it is refracted by the
lens in your eye and brought to focus on your
retina

23. Reflection of light
• Virtual image: laterally inverted image

24. • Angle of incidence (i) = Angle of reflection (r)
• Normal: A perpendicular line can be drawn to
the surface of the mirror, at the point of
incidence where the ray strikes the mirror

25. Refraction
• occurs as light passes across the boundary
between two media

26. Snell’s law
• Refraction index
• n = sin i / sin r
• n = Speed of light in medium 1
Speed of light in medium 2

27. • Critical angle:
– The angle of refraction becomes equal to 90°
• Total internal reflection:
– At greater angles of incidence, the ray are entirely
reflected back inside the medium

28. Optical fibres

29. Uses of Converging Lens

30. Three rules of refraction
• Any incident ray traveling parallel to the principal
axis of a converging lens will refract through the
lens and travel through the focal point on the
opposite side of the lens.
• Any incident ray traveling through the focal point
on the way to the lens will refract through the
lens and travel parallel to the principal axis.
• An incident ray that passes through the center of
the lens will in effect continue in the same
direction that it had when it entered the lens.

32. Dispersion of light
• The separation of visible light into its different
colours

33. Electromagnetic Spectrum

34. Sound
• A wave pattern of disturbance caused by the
movement of energy traveling through a medium
as it propagates away from the source.
• The source is some object that causes a vibration.
• The vibration disturbs the particles in the
surrounding medium; those particles disturb
those next to them, and so on.
• The wave carries the sound energy through the
medium, usually in all directions and less
intensely as it moves farther from the source.

35. What can you hear?
• Acoustic sound 20Hz to 20 000Hz
• Ultrasound higher then 20 000Hz
• Infrasound lower than 20Hz

36. Measuring the speed of
sound
• Use two microphones and a fast recording
device ( Oscilloscope)
• x = the distance between the microscopes
• t= time difference between signals (delay)
• Speed of sound = x/t

37. Loudness & Pitch
• We are all used to hearing different sounds.
We describe the differences in various ways:
loudness (loud, noisy, quiet, etc.) and high or
low pitch.
• The taller the amplitude, the louder the
sound. The more waves there are displayed,
the higher the pitch. Let's look at this in more
detail.

38. Echoes & Reverbation
• Reflection of sound waves off of barriers result
in some observable behaviours
• Perception of a sound usually endures in
memory for only 0.1 seconds
• Echo- more than 0.1 seconds (there will be a
small time delay)
• Reverb -less than 0.1 seconds (sound wave is
still held in memory, there is no time delay)

39. Uses of sound

40. Doppler’s effect
The Doppler effect can be described as the effect
produced by a moving source of waves in which
there is an apparent
upward shift in frequency
for observers towards
Whom the source is
Approaching and an
apparent downward
shift in frequency for
observers from whom the source is receding.

41. References
• http://www.dictionary.com/browse/transvers
e-wave
• https://www.berkeley.edu
• http://www.physicsclassroom.com/class/wave
s/Lesson-3/Reflection,-Refraction,-and-
Diffraction
• http://www.bbc.co.uk/schools/gcsebitesize/sc
ience/ocr_gateway_pre_2011/energy_home/
5_light1.shtml

42. References
• http://askmichellephysics.blogspot.co.za/2012
/04 /properties-of-waves.html
• http://whatis.techtarget.com/definition/soun
d-wave