2Introduction 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.
3Sound Where does sound come from? Where do you hear sound in the world around you?Click the ?
4Sound Where does sound come from? Where do you hear sound in the world around you?Click the ?
5Sound Where does sound come from? Where do you hear sound in the world around you?Click the ?
6Sound Where does sound come from? Where do you hear sound in the world around you?
7How 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??
8Waves! 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
9Sound WavesSound 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
10True or False, a guitar string and a speaker make a sound wave the same way? True False
11Both the guitar and speaker create sound waves by making vibrations in the air CORRECT!
12Not quite right…Both the guitar and the speaker make sound waves by making vibrations in the air
13Sound 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
14Parts of a WaveNow 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.
15Wavelength 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
16Which letter represents the wavelength of this wave? BA – green line B – blue line C – red line
17CORRECT!The wavelength is the distance between two crests or two troughs
18A – green line B – blue line C – red line Not quite, try again…Remember a wavelength is either from crest to crest or trough to troughACBA – green line B – blue line C – red line
19FrequencyFrequency 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)
20Which wave has a lower frequency? Red wave Blue wave
21CORRECT!The red line is a lower frequency because it has larger wavelengths and therefore less waves per second.
22Go 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
23Amplitude 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 soundHigh amplitudeLow amplitude
25Go 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 hasHigh amplitudeLow amplitudeGo back to review the information
26CORRECT!The taller the wave the bigger the amplitude. The bigger the amplitude the more energy a wave has.High amplitudeLow amplitude
27Different 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.-
28Waves have energyWaves 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
29Waves 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.
30ExamplesClick the link below to see an example of how waves in earthquakes transfer energy
31Quiz 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 materialBack to Back to Back toparts of waves Types of waves How wavesare madeBack toInteracting withmatterProceed to the quiz
32How does sound travel? Sound moves through the air into our ears Sound particles enter our earsBy loud noisesBy making vibrations in the air
33Click button to try again Back to studyingBeginning of quiz
59Here’s a cool song about waves: CONGRATULATIONSHere’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 quizBeginning of materialBeginning of quiz