1. Sound and Light

2. Sound
Sound is a mechanical wave that is vibrations transmitted through matter (solid, liquid, or gas)
The movement of the air molecules around a vibrating object is a sound wave

3. How does sound travel? Sound travels in waves
As sound travels away from an object the waves become weaker
Bill Nye “Waves” video clip:

4. A CYCLE is the complete back & forth motion of a vibration
Parts of a Sound Wave
A CYCLE is the complete back & forth motion of a vibration

5. amplitude, crest, trough, wave and cycle
Lets build a sound WAVE!
What you will need:
Yarn or string
Scissors
Glue
Colored pencils
Directions: Use your yarn/string to make the shape of a sound wave and glue it on your paper. Label the following parts:
amplitude, crest, trough, wave and cycle

6. Intensity and Volume of Sound
Intensity is the strength of a sound (measured in decibels)
Volume is the loudness or softness of a sound
FYI: Sounds above 130 decibels can damage your ears!

7. Pitch Pitch is the frequency of a sound (measured in hertz)
high frequency = high pitch (example: flute)
Low Frequency = low pitch (example: tuba)

8. Sound and Matter
Sound cannot travel if there are no molecules of matter for it to travel through
Sound causes particles of matter in air, liquid, or solids to vibrate and bump into another particle…think of it as the “domino effect”
Sound travels more quickly through substances with molecules that are closer together

9. Try it out
Try lining up dominoes close together and then farther apart.
Which moves faster?
This simulates how sound moves through particles that are closer and farther apart.

10. Sound and Temperature
In higher temperatures, sound moves more slowly since the air particles are farther apart

11. Try it out Rules: no running and no shoving!
Form two lines of people across the pod
One line will have people an arm’s length away representing cooler air (cool air is more dense)
The other line will have people 10 feet away from each other representing warmer air (warmer air is less dense)
The goal: start at one end and touch the next person in line one by one until you get to the end. The line that gets to the end first wins
This shows how sound travels through matter of
different temperatures

12. You can calculate the distance of a storm!
When you see a flash of lightening, count the number of seconds until you hear the thunder
Divide the number of seconds by 5 seconds per mile
The answer will tell you how many miles away the storm is!
It takes 6 seconds to hear thunder after a flash of lightening. How far away is the storm?
6 seconds divided by 5 seconds per kilometer
The storm is 1.2 kilometers away!

13. You can calculate the distance of a storm!
The purpose of this experiment is to watch lightning and hear thunder to give you clues about how far away you are from a storm.
Materials:
One “thunderstorm”
A stop watch (or the ability to say "one-Mississippi")
After you see a flash of lightning, count the number of seconds until you hear the thunder. (Use the stop watch or count "One-Mississippi, Two-Mississippi, Three-Mississippi," etc.)
2. For every 5 seconds the storm is one mile away. Divide the number of seconds you count by 3 to get the number of miles.

14. Questions to Discuss
1. What travels more quickly, light or sound? Why?
If you said light travels faster than sound, you're right! The lightning and thunder are happening at the same time, but light reaches you instantly, while sound takes longer.
2. Do you ever see lightning without hearing thunder? Why is that?
Some call that "heat lightning," but it is really lightning that is over 15 miles away and too far away for you to hear the thunder!
LOOK OUT if you see the lightning and hear the thunder at the same time!

15. Sound is bouncy! Sounds can bounce off objects
If a sound bounces back it is said to be reflected
Sound that bounces back is called an echo
Echos can be heard best when sound bounces off hard smooth surfaces

16. Using Sound in Science
We can use echo sound to find object below the surface of water…this is called sonar
We can use sound waves to see inside the human body…this is called an ultrasound

17. Let There Be Light! Light is a form of energy that can be seen
We see objects only
because light is
reflected off of them
Light is made of bundles
of energy called photons
Photons are tiny particles—a single photon is way too small to be seen

18. Light Waves Like sound, light travels in waves
Light waves move like waves in water
Light waves travel FAST! 300,000 km per second!

19. Parts of a Light Wave
Crest
Trough

20. Visible Light Light you see from the sun is “white light”
White light is made up of a band of colors called the “Visible Spectrum”…you can see these colors when you see a rainbow
You can use a prism see the colors in white light

21. Try It out!
Make your own prism activity

22. Light is Bouncy! Light bounces back or reflects when it hits an object
The only reason we can see objects is because they reflect light
You can see an image in a mirror because light waves are reflected

23. Different Types of Mirrors
Plane—a flat smooth surface
Concave – this has a surface that curves
inward…like the inside of a spoon
Convex – this has a surface that
curves outward…like
the back of a spoon
For a demonstration visit:

24. Plane Mirrors
This type of mirror gives the clearest image because the light reflects directly back

25. Concave Mirrors
FYI: The focal point is the point where reflected light rays from concave mirror come together in front of the mirror
If the image is located beyond the focal point of the mirror, it will appear upside down (inverted)
If the object is in front of the focal point of the mirror, it will appear right side up
If the object is at the exact focal point it will not appear at all!

26. Convex Mirrors
This type of mirror creates an image that looks smaller than the real object
Though the image is smaller, you can see much more area in a convex mirror…this is why convex mirrors are used a lot in store to help employees monitor retail areas

27. How is Light Bent?
Refraction – the bending of a wave as it moves from one material to another
Refraction Mini
Lab!

28. Take a moment to explore concave/convex lenses!
Lens - a curved piece of clear material that refracts light waves
Concave Lens – light that passes
through this lens are spread
apart
Convex Lens – Light that passes
through this lens is refracted
inward (the human eye has a
convex lens)
Take a moment to explore concave/convex lenses!

29. Nearsighted and Farsighted
Nearsighted – able only to
see things clearly that are
close up
Farsighted – able only to see
things clearly that are at a
distance

30. Scattering Light Waves Lab!