1. WAVES

2. SN#1
What are waves?
Wave – a disturbance that transfers energy from place to place.
Medium – the material thru which a wave passes
Waves travel through the medium without actually moving the medium with it.

4. Parts of a Wave Crest – the highest point of the wave
Trough – the lowest point of the wave
Wavelength – distance between one point on the wave and the same point on the next consecutive wave
Amplitude – The measure from the rest point to the crest or trough. The amplitude is a measure of how much energy is in the wave
Sound amplitude = volume

5. Crest
Wavelength
Amplitude
Trough

6. Amplitude and Frequency
SN #2
Amplitude and Frequency

7. What information about waves do amplitude and frequency provide
3 measurable properties of waves
1. Amplitude
2. Frequency
3. Wavelength
Amplitude is an important measurement because it tells you how much energy the wave has. In a sound wave, amplitude = volume
Frequency is how many waves pass a given point in a certain amount of time. Frequency is measured in Hertz (Hz), which is how many waves per second. In a sound wave, frequency = pitch

8. Relationships between……….
Amplitude and Frequency = none
Frequency and wavelength = inverse
when wavelength increases, frequency decreases.
As wavelength decreases, frequency increases.
Same amplitude – different wavelength

9. What are Mechanical Waves?
SN#3
What are Mechanical Waves?
Mechanical Waves are waves that must have a medium to travel through.
Medium = matter
The denser the medium the faster the wave travels.
Mechanical waves come in 2 forms:
Transverse
Longitudinal/Compression

10. Transverse Waves
Mechanical Waves where the particles of matter in the medium vibrate by moving back and forth and perpendicular (at right angles) to the direction the wave travels
Examples:
Ocean Waves
Seismic Waves

11. Longitudinal/Compression Waves
Mechanical waves in which the particles of matter in the medium vibrate by pushing together and move apart parallel to the direction in which the wave travels.
Examples:
Sound Waves
Waves on a
spring

12. What are the Characteristics of Sound
SN#6
What are the Characteristics of Sound
Sound is a form of energy that travels as Longitudinal/Compression waves.
Sound waves are produced by vibrations.
Characteristics of sound include volume which is determined by amplitude and pitch which is determined by wavelength.

13. High Frequency sounds have a short wavelength.
Objects vibrate quickly = High Pitch
Low Frequency sounds have a long wavelength.
Objects vibrate slowly = Low Pitch
High Pitch Sounds
Low Pitch Sounds
Bats
Flute
Whistle
Pipe Organ
Fog Horn
Frog Croak

14. What happens when sound is reflected & absorbed?
SN#7
What happens when sound is reflected & absorbed?
Sound wave behavior is influenced by the medium through which it is traveling.
Sound can be reflected, absorbed, diffracted and refracted.

15. Reflection
Sound waves can be reflected when a sound wave hits a barrier and bounces back.
Usually this happens when a sound wave hits a smooth flat surface.
This produces an echo

16. Absorption
Sound waves can be absorbed when a sound wave causes particles to vibrate which absorbs the sound and changes the sound to heat

18. What happens when sound is Diffracted and Refracted?
SN#8
What happens when sound is Diffracted and Refracted?
Sound waves can be refracted and diffracted.
Both refraction and diffraction have to do with bending the wave.

19. Refraction
In refraction waves are bent because the pass from one medium to another which changes their speed and wavelength causing them to bend.
This happens when we hear through a wall.

20. Diffraction
In diffraction, there is a change in the direction of waves as they pass through an opening or around a barrier in their path. 
Sound diffracting around corners or through door openings, allowing us to hear others who are speaking to us from adjacent rooms

22. How is sound present in daily life?
SN#9
How is sound present in daily life?
Oscilloscope – A device used to “record” sound
Ultrasound – sounds above which humans can hear. (20-20,000 Hz)
Ultrasound is used to create images inside the body which are difficult to see.
Ultrasounds are used to create pictures of organs like Kidneys and Heart.

23. Sonic Toothbrush – uses ultrasound to break plaque off teeth
Sonar – used to create images of the ocean floor.
Doppler Effect – The Doppler Effect is a phenomenon that occurs when the pitch changes because either the listener or the source of the sound is moving.
As the sound moves closer the wavelength (wl) becomes compressed = short wl

24. Short wl = High Pitch
After the source of the sound passes, wl is longer = lower pitch

25. What are Electromagnetic (EM) Waves
SN#12
What are Electromagnetic (EM) Waves
Electromagnetic waves are everywhere.
These waves can travel through a vacuum.
EM waves have many different wavelengths
The shorter the wavelength - the higher amount of energy they transmit.

26. All EM waves travel at the speed of light – 300,000 Km/s or 186,000 mi/s
EM waves have found valuable uses in our lives
The EM spectrum is all wavelengths of EM energy.

27. The Electromagnetic Spectrum

28. Radio Waves
*Longest Wavelength *Lowest Frequency *Lowest Energy Examples-TV signals, AM & FM radio signals Radio waves travel easily through the atmosphere and many materials.

29. Microwaves
*Shorter Wavelength than Radio Waves *Higher Frequency than Radio Waves *Higher Energy than Radio Waves Examples-Cell Phones and Radar Microwave ovens produce microwaves that cause water molecules in food to vibrate faster, which makes food warmer.

30. Infrared Waves
*Shorter Wavelengths than Microwaves *Higher Frequency than Microwaves *Higher Energy than Microwaves Examples- Sun, Fire and Radiator All objects emit infrared waves-usually given off by hot objects (stars, lamps, people and animals). Infrared radiation is the type of EM wave most often associated with heat.

31. Visible Light
*Shorter Wavelength than Infrared Light *Higher Frequency than Infrared Light *Higher Energy than Infrared Light Examples that reflect visible light: Sun, Light Bulbs Visible Light is the only part of the EM spectrum that the human eye can see. Red light= longest wavelength; lowest frequency Violet light= shortest wavelength; higher frequency White light= all colors mixed together

32. Ultraviolet Light
*Shorter Wavelength than Visible Light *Higher Frequency than Visible Light *Higher Energy than Visible Light Examples-Sun and special lamps (tanning bed) The wave can damage your skin and eyes; sun block can help filter out these frequencies. Uses: Sterilize medical equipment, help the produce vitamin D, harden dental fillings, and tanning.

33. X-Rays
*Shorter Wavelength than Ultraviolet Light *Higher Frequency than Ultraviolet Light *Higher Energy than Ultraviolet Light Examples- X-ray machines to view bones and airport security X-rays have enough energy to go through skin and muscle but are absorbed by the bone. Can be dangerous for a living organism.

34. Gamma Rays
*Shortest Wavelength *Highest Frequency *Highest Energy Examples- Sun, other stars and radioactive substances Used to kill cancer cells and fight tumors. Can be dangerous for a living organism.

35. SN # 13 What happens when EM waves are reflected and absorbed
The behavior of light waves (EM waves) can be manipulated by the medium through which they travel.
Reflection and absorption are two possible manipulations.

36. Reflection
Reflection of light occurs when EM waves (which light is a part) strike a barrier and bounce back.
It is light that is reflected which the human eye sees.

37. The Law of Reflection states that the angle of incident equals angle of reflection.

39. Absorption
This is when an EM wave disappears into a medium by changing to keep energy.
Darker Colors absorb EM waves
Lighter Colors Reflect EM waves.

40. SN # 14 What happens when EM waves are Diffracted and Refracted
EM waves can be manipulated.
Diffraction and Refraction cause the waves to bend and change speed.

41. Refraction
Occurs when EM waves encounter a new medium causing the waves to bend.
Your eyes refract light in order to focus the light on your retina.
Light bends when it goes from air to water.
This is why a straw in water looks broken.

42. Diffraction
Occurs when EM waves bend around a barrier or opening. This is why shadows look fuzzy.

43. SN #15 How are Mechanical and EM waves similar and different?
Mechanical Waves
Reflect, absorb, refract, diffract
Travel as longitudinal/
compression waves
Travel through
A vacuum
Carry energy
Travel at the same speed= 300,000km/sec
Travel in a medium
Have amplitude, wavelength, frequency
Travel at different speeds
Travel as Transverse waves
Have many valuable uses
Many different wavelengths

44. SN#16 How does the human eye see color?
The human eye gathers and focuses light.
The eye sees the color that is reflected.
The color of light is determined by the wavelength.
Light travels through the eye from the cornea, through the pupil, through the lens and strikes the retina.

45. *The cornea and lens refract light in the eye.
*Pupil size, controlled by the iris, determines how much light enters the eye.
*Light strikes the retina, forming a small inverted image.
The brain receive signals from the retina and interprets the image right side up.

46. *The retina has cells called rods that distinguish brightness- black and white
The retina also has cones that detect color.
The vitreous humour is the clear gel that fills the space between the lens and the retina

47. VITREOUS HUMOUR

48. Structure & Function IRIS colored part of eye controls light entering
PUPIL
black hole in iris
where light enters

49. Structure & Function SCLERA whites of the eye supports eyeball
provides attachment for muscles
LENS
converging lens
allows us to see objects near and far

50. Structure & Function CORNEA RETINA transparent bulge over pupil
focuses light (refracts) onto retina
RETINA
internal membrane
contain light-receptive cells (rods & cones)
converts light to electrical signal

51. Structure & Function OPTIC NERVE
Transmits electrical impulses from retina to the brain
Creates blind spot
Brain takes inverted image and flips it so we can see

52. Blind Spot On retina where optic nerve leads back into the brain
No rod or cone cells
Other eye compensates for this area
Try this test to prove you have a blind spot…

53. Close left eye and approach screen while staring at the letters…watch the dot!

54. Structure & Function RODS CONES 120 million cells detect brightness
(black & white)
for night vision
CONES
6 million cells
detect colour (RGB)
GANGLION CELLS
Detect movement and patterns

55. Normal Eye Focus
“Blind spot”

56. Video
YouTube
“The Human Eye” and “How the Human Eye Works”

57. The Human Eye
Refractive index of lens different for each wavelength (colour)
Cool colours (blues) appear closer; warm colours (reds) further away
Agree?

58. Others see the opposite.
Most people see the red,
Closer than the blue.
Others see the opposite.
How about you?

59. Are you seeing spots?

61. Are these lines bent….?

62. …or straight?

66. What is wrong with with this sentence?
Reading
What is wrong with with this sentence?
Aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.

67. Read This Out Loud.

68. Are You Sure? Read again.