Light enters a diamond and undergoes total internal reflection within the diamond due to the high refractive index of diamond. This causes the light to exit the diamond at different angles, producing the sparkling effect. The facets on cut diamonds are designed to maximize the internal reflections and sparkling. Diamonds appear white due to dispersion of light into the visible spectrum by the crystal structure of diamond.

1. WAVES
● What are waves? What aren't they? Give some
examples.

2. WAVES
A wave consists of oscillations which move
without carrying matter with them.
The oscillations carry energy.
A wave can be used to carry the energy itself, or it
can be used to carry a signal.

3. Pulse
A pulse is a single wave 'bump' or a “disturbance”.
A pulse can easily be sent down a string or spring.
A wave is made of lots of regular pulses.

4. A Nice Animation
http://upload.wikimedia.org/wikipedia/commons/7/7

5. Amplitude
Amplitude determines how much energy the waves have.
More amplitude = brighter light, louder sound etc.
Wavelength = λ = lowercase (Greek) 'lambda'.
What is the relationship between v, f and λ?
http://upload.wikimedia.org/wikipedia/commons/f/fa/Wave.JPG

6. Transverse Waves
https://encrypted-tbn0.google.com/images?q=tbn:ANd

7. Longitudinal Waves
Longitudinal waves are the opposite of transverse waves.
The direction of propagation is the same as the direction of
vibration in the medium.
https://encrypted-tbn1.google.com/ima

8. Example
William is swimming at a beach with waves
constantly coming from the sea. He estimates that
the distance between the wave crests is 6m, and
two wave crests pass him every second. How fast
are the waves travelling?

9. Example 2
David shouts across the room at Aska. He shouts
with a low frequency of 5000 Hertz, and the
waves travel at a speed of 340 m/s. What is the
wavelength of David's voice?

10. Quick Review
● Write a definition in your own words of:
A. Frequency
B. Wavelength
C. Wave speed
D. Amplitude
E. Crest
F. Trough
● State and explain the wave equation, including
explaining why it works.

11. A. What is the time period of a wave if two waves
pass every twenty seconds?
B. What is the frequency of the wave from A?
C. Hard: what is the relationship between time period
and frequency (for any wave)? Write it like a math
equation, using f for frequency and T for time period.
It is ok if you can't do this question :)

12. The speed of sound in air is about three hundred and forty metres per
second.
10. What is the frequency of a sound wave with a wavelength of 6.8
meters?
11. Humans can hear approximately twenty hertz to twenty kilohertz.
Calculate the minimum and maximum wavelengths humans can hear.
12. The speed of light is 300 000 000 (3 * 108) meters per second.
Calculate the wavelength of red light, given that it has a frequency of 500
000 000 000 000 (5 * 1014) Hertz.

13. The Microwave
● Calculate the wavelength of the microwaves in
a microwave oven.

14. Maxence is swimming in a wave pool. The wave
generator creates two waves each second, and
they travel at a speed of three metres per second.
A. Will Maxence notice the wave crests or
troughs?
B. How far apart are two crests or two troughs?

15. Quantity Symbol Formula Unit
Speed/
V
metres per
velocity s = f*λ second (m/s)
f = v/λ Hertz (Hz)
λ
(lambda)

16. Sound
● Sound is a longitudinal wave.
● It can travel through liquids and all gases.
● An oscilloscope can convert sound waves to
visible transverse waves.
● Humans can hear from around 20 Hz to 20
kHz, and the range decreases with age. A
phone can typically carry waves ranging from
300Hz to 3.4kHz.

17. Pitch and Loudness
● Recall humans can hear from 20 Hz to 20 kHz.
● Frequency = pitch
● Amplitude = volume
http://www.sciencelearn.org.nz/Contexts/The-Noisy-Reef/Sci-Media/Images/Graphs-of-sound-
waves

18. Frequency Ranges
● Drum = 20Hz
● Low note from a singer = 100Hz.
● High note from singer = 1000Hz.
● Whistle = 10 000 Hz.
All images from wikimedia commons.

19. Testing your Speakers
● Use onlinetonegenerator.com to test the speaker in
your computer OR smartphone (or other device).
● Either wear headphones (not too loud!) or work in
groups, for obvious reasons!

20. Testing Skype
● Use a tone generator software (tonegen is free
but 'expires', or use a smartphone) to test the
frequency response range of skype (or your
microphone).

21. Noise and decibels (dB)
● Noise is unwanted sound.
● Sound level is measured in decibels (dB).
http://impact.books.officelive.com/ProtectYourHearing.asp

22. Sound and Waves Review
1. What is a wave?
2. Describe the two main types of waves.
3. State the wave equation, and the formula
which relates them.
4. Name one property of a wave which is not part
of the wave equation. How do we observe this
property of sound waves.
5. How do we observe frequency of sound
waves?
6. State the maximum audible range of humans.

23. Ripple Tank Here
● Either the real one or a virtual one :)
http://phet.colorado.edu/en/simulation/wave-interfer

24. Go to phet.colorado.edu/web-pages/simulations-base.html
● Go to Sound and Waves. Choose “Water” (top left), “one drip” and “no barrier”
(centre right).
● Devise an experiment to calculate the speed of the waves in the water.
● Aim: To measure the effect of frequency and amplitude on wave speed in water.
● Prediction: As the frequency increases, the wave speed will ____________
because ___________________________________________.
As the amplitude increases, the wave speed will ____________
because ___________________________________________

25. Speed, Frequency, Wavelength
The velocity of waves in a medium is not
affected by amplitude or frequency.
● What happens to the wavelength as the
frequency increases?
● What happens to the frequency as the
wavelength increases?
● Hard:
What is the mathematical relationship between
frequency and wavelength?

26. Wavefronts
● A wave can be drawn as a series of lines, where each
line represents a crest.
● We can also draw them as a line through the middle of
the wave, often called a ray.
● What is the mathematical relationship between the ray
and the wavefronts?
http://www.studyphysics.ca/newnotes/20/unit03_mechanicalwaves/chp141516_waves/lesson43.h

27. Reflection of Waves
● The region two different media meet is called a
boundary.
● At a boundary a wave can reflect.
http://science.jburroughs.org/mschober/waveslite/prob

28. Refraction of Waves
● If a wave enters a
different medium, its
speed will probably
change.
● A change in speed
causes a change in
direction.
● Depth of water
changes the speed
of waves.
Image from Giancoli Physics, Sixth Edition removed.

29. Diffraction
● As waves pass a barrier or through a gap in a
barrier, they spread out.
● The diffraction is generally only noticeable if the
gap is not much larger than one wavelength.
http://innovativescience.blogspot.com/2011/02/di

30. Textbook work
● All questions on page 95.

31. The Electromagnetic Spectrum
http://upload.wikimedia.org/wikipedia/commons/thumb/c/cf/EM_Spectrum_Properties_edit.svg/675p
x-EM_Spectrum_Properties_edit.svg.png

32. Electromagnetic Spectrum
Wave Approximate Approximate Uses
Frequency Wavelength
Radio waves 103m
Microwaves 10-2m
Infra Red 10-5m
Waves
Visible Light 5 *10-7m
Ultraviolet Light 10-8m
X Rays 10-10m
Gamma Rays 10-12m
seeing things; for cell phones and for heating things which contain water; transmitting
signals; photographing bones which can't be seen with visible light; remote controls;
identifying genuine or forged documents, and for purification of air and water; to sterilise
food and seeds, and for cancer treatment

33. The words
seeing things; for cell phones and for heating
things which contain water; transmitting signals;
photographing bones which can't be seen with
visible light; remote controls; identifying genuine
or forged documents, and for purification of air
and water; to sterilise food and seeds, and for
cancer treatment

34. Signals
● Electromagnetic waves are used to carry signals.
● A continuous variation is called an analog signal,
whereas digital signals are represented as numbers.
Most early communications devices used analogue,
while most modern devices use digital (exceptions?).
http://news.bbc.co.uk/2/hi/technology/6142998.stm

35. Signals
● Electromagnetic waves are used to carry signals.
● A continuous variation is called an analog signal,
whereas digital signals are represented as numbers.
Most early communications devices used analogue,
while most modern devices use digital (exceptions?).
http://news.bbc.co.uk/2/hi/technology/61429

36. Radio Waves
● Radio waves are used to carry signals for radio,
TV and mobile phones.
● Either the frequency or amplitude must be
changed (modulation) to carry the signal.
http://www.softwareforeducation.com/

37. Frequency Bands
● Different frequencies (“bandwidths”) are used for
different applications. They must be managed(as
a resource) to ensure that people don't use the
same frequency in the same place.
http://en.wikipedia.org/wiki/Radio_spectrum

38. AM and FM
● AM radio waves can diffract around hills and
mountains, so are best for rural areas.
● FM signals are better quality, and are generally
used in urban areas.
http://scienceaid.co.uk/physics/wa

39. Fibre Optics
● Fibre optics are thin
glass cables which
carry electromagnetic
radiation(IR or visible
light) inside them.
● They are thinner and
lighter than electrical
wire, and lose less
signal over long
distances.
http://upload.wikimedia.org/wikipedia/commons/thumb/4/49/Fibreoptic.jpg/220px-Fibreoptic.jpg

40. Radio Waves
● Radio waves are used to carry signals for radio,
TV and mobile phones.
● Either the frequency or amplitude must be
changed (modulation) to carry the signal.
http://www.softwareforeducation.com/wikileki/index.php?title=FM

41. Diffraction of AM and FM
● AM radio waves can diffract around hills and
mountains, so are best for rural areas.
● FM signals are better quality, and are generally
used in urban areas.
http://scienceaid.co.uk/physics/waves/radio.html

42. Frequency Bands
● Different frequencies (“bandwidths”) are used for
different applications. They must be managed(as
a resource) to ensure that people don't use the
same frequency in the same place.
http://en.wikipedia.org/wiki/Radio_spectrum

43. Absorption by the Atmosphere
http://en.wikipedia.org/wiki/File:Atmospheric_electromagnetic_opacity.svg

44. The Dog at the Beach
http://www.flickr.com/photos/velo4it/1746214612/

45. How the Dog Runs
Sand Sea
http://commons.wikimedia.org/wiki/File:2009-11-19_(31)_Branch,_Ast.JPG
http://commons.wikimedia.org/wiki/File:Brittany_Spaniel_Dog.jpg
http://commons.wikimedia.org/wiki/File:Dog_retrieving_stick.jpg

46. How the Dog Runs
Sand Sea Sand
http://commons.wikimedia.org/wiki/File:2009-11-19_(31)_Branch,_Ast.JPG
http://commons.wikimedia.org/wiki/File:Dog_retrieving_stick.jpg
http://commons.wikimedia.org/wiki/File:Brittany_Spaniel_Dog.jpg

47. Light
Light is an electromagnetic wave, therefore:
1) It travels at a speed of _________.
2) It can travel through _________.
3) As a wave, it can d______, r_______ or r________.
●Light can be drawn as rays, where the ray is perpendicular
to the w___________.
●Light (rays) must travel in s______ l_______.
●The eye detects light (more later). Some things emit light
(eg __________) while most things we see reflect light (eg
_____________________)
http://commons.wikimedia.org/wiki/File:Gluehbirne_2_db.jpg

48. Reflection of Light
● Most objects reflect light but scatter it in all directions.
Mirrors (and other shiny surfaces) reflect light so that
they produce images.
● Reflected rays follow two rules:
ι ρ
θ =θ
1. The angle of incidence equals the angle of reflection.
2. The incident ray, normal and the reflected ray all lie in
the same plane.
Angle of
incidence Angle of
reflection
http://upload.wikimedia.org/wikipedia/commons/b/b2/Ray_optics_diagram_incidence_reflection_an
d_refraction.svg

49. Images from Plane Mirrors
● Plane mirrors form images which are:
1. the same size
2. the same distance from the mirror
3. laterally inverted (left and right swapped).
● A great site below:
http://www.kss.sd23.bc.ca/staff/jstracha/physics_11/course_material/unit8/U08L01/pages/ray7_plan
e_jpg.htm

50. Bookwork
● Page 85 and 87.

51. Refraction
● When light enters a different
medium, it changes
direction, unless it enters
along the normal (an angle
of incidence of ______).
● As light enters a more
dense medium, it slows
down, and bends
____________ the normal.
● As light enters a less dense
medium, it speeds up, and
bends ____________ from
the normal. http://www.daviddarling.info/images/refraction.gif

52. The Brain
● Recall that the part of the brain which
subconsciously controls the eye 'thinks' that
light always travels in straight lines.
http://www.mikecurtis.org.uk/light3.gif

53. Why Something Looks Bent in Water
http://upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Pencil_in_a_bowl_of_water.svg/1000p
-Pencil_in_a_bowl_of_water.svg.png

54. Refraction and Colour
● High frequency light (eg violet) is bent more
than low frequency light (eg red).
● This is why a prism can separate white light into
its different colours.
● This process is known as dispersion.
http://upload.wikimedia.org/wikipedia/commons/0/06/Prism_rainbow_schema.png

55. Angles

56. The Semi-Circular Block
When light is shone towards the centre of
the (semi) circle, the angle if incidence is
always ________.

57. The Critical Angle is the angle for which the
refracted ray has an angle of refraction of 90°.

58. Total Internal Reflection
● When light travels from a MORE dense
medium to a LESS dense medium, it bends
_____ _______ the normal.
● If the refracted light has an angle of refraction
greater than the critical angle, the light is
instead reflected. This is called total internal
reflection.

59. Determining The Critical Angle
● Determine the critical
angle for perspex.
● While you are using the
ray boxes, also observe
and draw how light
refracts through a
rectangular perspex
block, and the convex
and concave lenses.
http://www.one-
school.net/Malaysia/UniversityandCollege/SPM/revisioncard/physics/light/images/criticalangle.pn

60. http://upload.wikimedia.org/wikipedia/commons/thumb/c/c0/Total_internal_reflection_of_Chelonia_
mydas_.jpg/800px-Total_internal_reflection_of_Chelonia_mydas_.jpg

61. Why Do Diamonds Sparkle
http://roniece.com/wp-content/uploads/2010/09/sun.gif
http://commons.wikimedia.org/wiki/File:CZ_brilliant.jpg

62. Questions
● Page 89 & 91.
speed of light in vacuum
refractive index =
speed of light in medium

63. Convex Lenses
A convex lens can produce a real image.
A real image forms when light leaves an object
and meets somewhere else. The object appears
to be where its image is.

64. Images
An image can be:
●enlarged, diminished or the same size
●upright or inverted
●real (light focusses there) or virtual (light looks
like it focuses there).

65. Real Images
A real image can be focussed onto a screen. The object
appears to be where the image is. If it is bright and clear
enough, a real image can trick the eye (and person) into thinking
that something is really there.
Ray 1: Parallel to the principle axis and Ray 2: Through the optical centre.
through the focus.
principle axis
C F F
Ray 3: Through the closest focus and
then parallel to the principle axis.
http://upload.wikimedia.org/wikipedia/commons/a/af/Pencil_drawing.png

66. CAMERA
Film/
CCD
If the image were a very, very long way away, what
would the distance from the lens to the film be?
http://commons.wikimedia.org/w/index.php?title=File:Person_Outline_2.svg&page=1

67. Answer: In the animation, as the man
CAMERA walked closer to the camera, the lens
moved towards the man in order for the
image to remain focussed on the film.
Film/
CCD
If the image were a very, very long way away, what
would the distance from the lens to the film be?

68. CAMERA
Film/ CCD
F
At this point, the image of the man is
focussed on the film.

69. CAMERA
Film/ CCD
F
When the man walks closer, the(larger)
image forms behind the CCD.

70. CAMERA
Film/ CCD
F
To keep the image focussed on the
CCD, the lens is moved towards the
man. The image is larger, which makes
sense because the object being
photographed is closer.

71. An Excellent Site to Try Out
● http://www.phy.ntnu.edu.tw/ntnujava/index.php?topi
● In this simulation it's possible to try many
different locations for objects and images.