1. Waves
7th grade science

2. Introduction Audience: This lesson is for students in 7th grade.
Objective: Students will be able to identify a wave, understand that a wave is produced by vibrations in matter and demonstrate how waves transfer energy when they interact with matter.

3. Sound Where does sound come from?
Where do you hear sound in the world around you?
Click the ?

4. Sound Where does sound come from?
Where do you hear sound in the world around you?
Click the ?

5. Sound Where does sound come from?
Where do you hear sound in the world around you?
Click the ?

6. Sound Where does sound come from?
Where do you hear sound in the world around you?

7. How does sound travel?
We have an idea of where sound comes from, but how does it get from where it is to us so we can here it?
How does sound travel? ?

8. Waves! Let’s Explore Sound travels in waves. But what is a wave?
A wave is caused when vibrations, or movement, is caused in matter, or the stuff around us. For example, the speakers on a radio use energy to vibrate the air around it. These vibrations travel through the air in a wave and eventually reach your ear which is what allows you to hear.
Let’s Explore

9. Sound Waves
Sound waves are caused when objects create vibrations. This energy vibrates the air around it creating a wave.
When you pluck a guitar string, the string vibrates and produces a wave.
If you look at a speaker when it is playing you will see it vibrate. This produces a sound wave the same way the guitar does

10. True or False, a guitar string and a speaker make a sound wave the same way?
True False

11. Both the guitar and speaker create sound waves by making vibrations in the air
CORRECT!

12. Not quite right…
Both the guitar and the speaker make sound waves by making vibrations in the air

13. Sound Waves You Can See http://www.youtube.com/watch?v=_diS1twUbcU
Take a look at this video of a speaker creating sound waves in water. The water allows us to see the waves that are being created since we can’t see the air around us. (click on the link to play video)
Look for the vibrations in the water when the speaker is on and watch them stop when the speaker stops playing

14. Parts of a Wave
Now that we know that sound travels in waves there must be different parts of a wave because we hear different sounds.
There are 3 things that make up a wave. They are wavelength, frequency and amplitude.

15. Wavelength Crest Crest Trough Trough
The wavelength is how far apart the waves are. This can be measure from either crest to crest or trough to trough. This is equal to one wave length.
Crest – top of the wave Trough – bottom of the wave

16. Which letter represents the wavelength of this wave?B
A – green line B – blue line C – red line

17. CORRECT!
The wavelength is the distance between two crests or two troughs

18. A – green line B – blue line C – red line
Not quite, try again…
Remember a wavelength is either from crest to crest or trough to trough A C B
A – green line B – blue line C – red line

19. Frequency
Frequency is the number of waves that travel past a point every second. Therefore shorter wavelengths means higher frequency and longer wavelengths means a lower frequency.
The more waves the higher the frequency.
(Click the speaker to listen)
Fewer waves means a lower frequency.
(Click the speaker to listen)

20. Which wave has a lower frequency?
Red wave Blue wave

21. CORRECT!
The red line is a lower frequency because it has larger wavelengths and therefore less waves per second.

22. Go back to review the information
Not quite…
Remember the frequency is the number of waves per second. The lower the frequency, the fewer waves per second. These waves will be more spaced out.
Go back to review the information

23. Amplitude High amplitude Low amplitude
The third part of waves is called the Amplitude. The amplitude is how much energy a wave has. If it is a sound wave then a bigger amplitude will mean it’s a louder sound
High amplitude
Low amplitude

24. Which wave has a biggest amplitude?1 2 3

25. Go back to review the information
Not quite…
Remember, amplitude is based on how tall the waves are. The taller the waves the bigger the amplitude and more energy the wave has
High amplitude
Low amplitude
Go back to review the information

26. CORRECT!
The taller the wave the bigger the amplitude. The bigger the amplitude the more energy a wave has.
High amplitude
Low amplitude

27. Different types of waves
There are other waves besides sound waves. Waves also move through the water and waves known as seismic waves cause the Earth to shake during and earthquake. -

28. Waves have energy
Waves move through matter, they do not push matter along. For example, waves in the ocean are not carrying a lot of water with them but are simply moving through the water. Watch this video to learn more about waves in the ocean and see an example

29. Waves Interacting with Matter
When waves interact with matter, the energy they are carrying is transferred to that object causing it to vibrate. With sound waves that allows us to hear and with seismic waves during earthquakes, that can make buildings fall down. Click to the next slide to see an example of how waves interact with buildings and can knock them down.

30. Examples
Click the link below to see an example of how waves in earthquakes transfer energy

31. Quiz Time Proceed to the quiz
In the upcoming quiz you will be answer questions about the different parts of waves, different types of waves, how waves are made and how they interact with matter. If you aren’t sure about any of those, go back to that section and review the material
Back to Back to Back to
parts of waves Types of waves How waves
are made
Back to
Interacting with
matter
Proceed to the quiz

32. How does sound travel? Sound moves through the air into our ears
Sound particles enter our ears
By loud noises
By making vibrations in the air

33. Click button to try again
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34. Next Question
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35. True or false: A speaker can create sound with out creating vibrations?

36. Click button to try again
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38. Which of these is not a part of a wave?
The wavelength
The frequency
The threshold
The amplitude

39. Click button to try again
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40. Next Question
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41. Frequency is… The size of the wavelength Number of waves per second
The amount of energy a wave has
None of the above

42. Try Again Review what we learned earlier. Click button to try again
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43. Next Question
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44. Waves transfer ______ to matter it interacts with.
Water
Information
Energy
Earthquakes

45. Click button to try again
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46. Next Question
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47. In this video, vibrations are being transferred from what to what?
Water  Speaker
Speaker  Water
Ground  Water
Seismic waves  Sound waves
Click link to play video

48. Click button to try again
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50. Which wave has a larger amplitude, green or red?

51. Click button to try again
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53. When a wave interacts with matter, what happens?
The energy the wave is carrying is transferred
The wave moves through the matter
The wave stops moving
The matter absorbs the waves energy

54. Click button to try again
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55. Next Question
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56. True or false: This is an example of a wave.

57. Click button to try again
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59. Here’s a cool song about waves:
CONGRATULATIONS
Here’s a cool song about waves:
You completed the quiz. Click below to go back to the beginning to review the material or to retake the quiz
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