1. 3
Chapter 4
Sound & Light

2. Sound Sound travels from one place to another as sound waves
A sound wave is a
longitudinal wave that can only travel through matter (Solids, liquids, gases)
Vibrations
produce sound waves by
moving molecules in air.

3. How does the ear work? Sound waves are sent.
The outer ear “catches the sound waves”.
The middle ear takes the sound waves and “vibrates” the eardrum.
The inner ear sends the messages to the brain.
Middle Ear
Outer Ear
Sound Waves
Inner Ear
The brain puts it together and hooray! You hear your favorite song on the radio.

5. How sound waves travel! Outer ear – Catches sound waves Middle ear –
Vibrates
Ear
Drum
Inner ear –
Sends
Message To
Brain

6. Sound waves are made up of two parts:
Rarefactions
Compressions
The tuning fork causes molecules in the air to
move closer and then farther apart

8. Like other waves, a sound wave can be described by its:
Wavelength
Frequency
Wavelength:
distance from center of
rarefaction to next rarefaction (vice versa)
Frequency:
The # of wavelengths that pass
a given point in one second
The unit for
frequency is
Hertz (Hz)

9. Speeds of Sound Waves A sound wave’s speed increases when
the material’s density increases.
Solids and liquids are dense than gases.
more
Sound waves usually travel faster in
solids
than in or
liquids
gases.
The speed of sound waves increase as the temperature
increases.

11. If sound travels faster in water than in air…then why is it harder to talk to someone underwater?
Sound couples poorly moving from air to water.
Your lungs provide the burst of air when talking underwater.
In order for someone underwater to hear you, the sound waves have to go from the air in your mouth to the water surrounding you.
This causes the sound waves to get reflected where the air meets the water.

12. Pitch Pitch: how high or low a sound seems
A sound wave with a higher frequency has a pitch.
higher
A sound wave with a lower frequency has a pitch.
lower

14. Loudness Loudness is the human sensation of
how much energy a sound wave carries
A shout carries more than a whisper.
energy
The energy that the wave carries relates to its
amplitude.

15. Loudness (cont’d) The more energy a wave has the
greater the amplitude.
A is one way to compare the loudness of sounds
decibel scale

16. Echo
An echo is a
reflected sound wave.

17. Some animals use to locate their prey and detect objects.
Animals such as dolphins and bats send out and when those waves hit
an object it bounces back
echolocation
sound waves
vibrations.

18. Sound Travels Through Matter
Liquids
Some sounds that we hear travel through water.
Sound waves travel faster through water than through the air.
Sonar is the way to use sounds to locate objects under water.
Gases
Most of the sounds we hear travel through gases, such as air.
Sound waves travel slowly through the air.
For example: Sound from a bell, a horn, or an alarm clock travels through the air.
Solids
Some sounds that we hear travel through solids.
Sound waves travel very fast through solids.
For example: When you hit a drum, it vibrates, then the sound travels through the air, to your ears.

20. Ultrasound
Ultrasound scanners convert high-frequency sound waves to images of internal body parts.
The sound waves reflect from structures within the body.
The scanner analyzed the reflected waves and produces images called sonograms.

22. Breaking the Sound Barrier
When the vehicle (jet) exceeds the speed at which sound travels.
The cone of vapor you see is the existing moisture in the air being condensed by pressure wave created by the vehicle creating a cloud.

23. Lesson 2: Light

24. Light Light is a type of wave called an
electromagnetic wave.
Light does not need a to travel through.
A medium is
Light can travel through a
An example of a vacuum is the
medium
a material through which
a wave travels.
vacuum.
space between Earth and the Sun.

25. Light travels at different speeds through different mediums

26. Electromagnetic Spectrum
The electromagnetic spectrum includes
Wavelengths are measured in
a range of electromagnetic waves.
nanometers.
Wavelength is 400nm
Wavelength is 700nm

27. A is something that emits (gives off) heat.
Examples of light sources include:
A light ray is a
light source
burning candle, sun, light bulb
narrow beam of light that
travels in a straight line.
Laser

28. We see things because they
A is the process of light striking an object and bouncing off.
reflection
We see things because they
light into
reflect
our eyes.
Homework

29. Transparent: almost all light passes through object
Depending on how materials interact with light, they are classified as:
transparent, translucent, or opaque
Transparent: almost all light passes through object
Translucent:
most light passes through & blurry image forms
Opaque:
no light passes through it

31. When light waves interact with matter they can be:
Transmitted
2. Absorbed
3. Reflected
light waves travel through a material
(transparent object)
light waves are converted to other forms; translucent object
light waves bounce of surface of material
(opaque object)

32. Law of Reflection
The angle of incidence is always equal to the angle of reflection.
Normal
Incident ray
Reflected ray
Angle of incidence
Angle of reflection
Mirror

33. Scattering occurs when light waves
HAVE YOU EVER SEEN DUST PARTICLES FLOATING IN THE AIR WHEN A BEAM OF SUNLIGHT SHINES THROUGH A WINDOW?
This is an example of
scattering.
Scattering occurs when light waves
travelling in one direction are made to travel in many directions.

34. Refraction
Light waves change when they travel from one material to another.
The bending of a wave as it moves from one material to another is called
This is due to a change in
direction
refraction.
speed.

35. Light
Light is slower when passing through
dense materials.

36. Retina Cones Rods 6 million 120 million
Response to light waves with different wavelengths allow you to see different colors.
3 types – each detecting a different wavelength.
In some people, not all 3 function properly = color blindness/color deficiency.
Rods
120 million
Allow you to see in dim light
Black and white signals – does not allow you to see color.

37. People with color deficiency cannot see a number in this picture!

38. How your eye works

39. LESSON 3:
MIRRORS & LENSES

40. Regular Reflection Light waves reflect off a
mirrorlike surface.
The reflects light rays traveling in the same direction at the same angle.
smooth surface

41. Diffuse Reflection
When a surface is not smooth the reflected angle travels
in many different
directions.

42. Mirrors
A is any reflecting surface that forms an image by regular reflection.
mirror
Plane Mirror:
Convex Mirror:
Concave Mirror:
Flat surface
Same image, just reversed left to right
Curved Inward
Objects can appear upside down or right-side up
Curved outward
Objects are smaller and right-side up

43. Cosmetic mirrors are often
concave mirrors.
Image becomes
magnified.
Convex mirrors are often used for
safety purposes.

44. Lens A lens is a transparent object with at least
one curved side that causes light to change direction
Convex Lenses
Curved outward
Thicker in the middle
Objects appear larger

45. Glasses for nearsightedness (can’t see far)
Concave Lens
Curved inward
Thicker at the sides
Object is shown smaller
Glasses for nearsightedness (can’t see far)

46. How do objects get their color?
Objects light.
Colors depend on the of the light waves it reflects.
reflect
wavelengths
The rose looks red because all the other wavelengths are absorbed but red is reflected.

47. combination of all light waves.
White light is a
combination of all light waves.
Neon lights emit different colors.
(give off)
The appearance of an object changes under different lights.