1. Characteristics of Waves

2. What is a wave? A wave is a action that causes energy to travel from one place to another. – Energy is a push or a pull on an object multiplied by the distance the object travels (W=FxD) There are two kinds of waves that we will learn about – – Mechanical and Electro-magnetic A wave is a action that causes energy to travel from one place to another. – Energy is a push or a pull on an object multiplied by the distance the object travels (W=FxD) There are two kinds of waves that we will learn about – – Mechanical and Electro-magnetic

3. Mechanical Waves Mechanical waves transfer energy from one place to another through a medium. A medium is any type of matter like a string or air or water. Mechanical waves vibrate the medium and that’s how the energy transfers from one end of the medium to the other. Mechanical waves transfer energy from one place to another through a medium. A medium is any type of matter like a string or air or water. Mechanical waves vibrate the medium and that’s how the energy transfers from one end of the medium to the other.

4. Mechanical Waves There are two type of mechanical waves – – Transverse – Longitudinal Transverse waves have the energy move perpendicular to the medium. There are two type of mechanical waves – – Transverse – Longitudinal Transverse waves have the energy move perpendicular to the medium.

5. Mechanical Waves Longitudinal waves allow energy to move parallel to the medium.

6. Properties of Waves Just like with any object, we need to label parts so we can discuss and figure out how to use the object to the best of its ability. Waves have parts that we will identify and figure out why waves are important… Just like with any object, we need to label parts so we can discuss and figure out how to use the object to the best of its ability. Waves have parts that we will identify and figure out why waves are important…

7. Properties of Transverse Waves Crest Trough Wavelength Amplitude Frequency Crest Trough Wavelength Amplitude Frequency

8. Properties of Longitudinal Waves Compression Rarefaction Amplitude Frequency Wavelength Compression Rarefaction Amplitude Frequency Wavelength

9. Wave Speed Speed is a measurement of how far an object travels and how long it takes to get there. For a wave, the speed is measured as follows: – Speed = wavelength X frequency The label for this calculation is Hertz (Hz) Speed is a measurement of how far an object travels and how long it takes to get there. For a wave, the speed is measured as follows: – Speed = wavelength X frequency The label for this calculation is Hertz (Hz)

10. Wave Speed Examples A wave has a wavelength of 2 mm and a frequency of 3 Hz. At what speed does the wave travel? The speed of a wave on a guitar string is 142 m/s and the frequency is 110 Hz. What is the wavelength of the wave? A wave has a wavelength of 2 mm and a frequency of 3 Hz. At what speed does the wave travel? The speed of a wave on a guitar string is 142 m/s and the frequency is 110 Hz. What is the wavelength of the wave?

11. Interactions of Waves Waves can bump into other objects. This “bump” is called an interaction. When a waves hits an object and can’t pass through it - it’s called a reflection. Think of a reflection like a bounce. The wave hits a surface and the entire wave bounces off. Waves can bump into other objects. This “bump” is called an interaction. When a waves hits an object and can’t pass through it - it’s called a reflection. Think of a reflection like a bounce. The wave hits a surface and the entire wave bounces off.

12. Interactions of Waves Reflection

13. Interactions of Waves Another type of wave “bump” is a refraction. Refractions occur when the wave goes through an object. Refraction is about the speed of the wave when it enters another medium and it changes speed as it leaves. Think of a refraction like a bend. The wave goes through the surface in one point and leaves in another. Another type of wave “bump” is a refraction. Refractions occur when the wave goes through an object. Refraction is about the speed of the wave when it enters another medium and it changes speed as it leaves. Think of a refraction like a bend. The wave goes through the surface in one point and leaves in another.

14. Interactions of Waves Bob is looking for the fish but can’t see exactly where they are because of the refraction of the image Bob is looking for the fish but can’t see exactly where they are because of the refraction of the image

15. Interactions of Waves Diffraction – when the wave goes through a barrier and then spreads out. Best way to think about this is how kids travel to the cafeteria. You are only allowed to enter through a small doorway and then you spread out to fill up the entire room. Diffraction – when the wave goes through a barrier and then spreads out. Best way to think about this is how kids travel to the cafeteria. You are only allowed to enter through a small doorway and then you spread out to fill up the entire room.

16. Interactions of Waves This is an example of diffraction.

17. Interactions of Waves Another time of wave interaction is called Interference. Interference occurs when two or waves meet. There are two types of interference – Constructive – Destructive Another time of wave interaction is called Interference. Interference occurs when two or waves meet. There are two types of interference – Constructive – Destructive

18. Interactions of Waves Constructive Interference happens when two waves meet and combine to become larger.

19. Interactions of Waves Destructive Interference occurs when two waves meet and they get smaller or cancel each other out.

20. Interactions of Waves Now when waves just pass through each other and keep their own energy – it’s called a Standing Wave. Standing waves have nodes (zero amplitude) and anti-nodes (maximum amplitude) Now when waves just pass through each other and keep their own energy – it’s called a Standing Wave. Standing waves have nodes (zero amplitude) and anti-nodes (maximum amplitude)

21. Interaction of Waves When waves interact with each other, sometimes they match or mimic each other. This is called Resonance. When waves interact with each other, sometimes they match or mimic each other. This is called Resonance.

22. Seismic Waves Waves produced by the earth are called seismic waves. When energy is released from the Earth it travels in all directions, but how it travels and how long it takes to reach a reference point …. Well…. That’s how scientists classify the waves. There are S waves, P waves, and surface waves. Waves produced by the earth are called seismic waves. When energy is released from the Earth it travels in all directions, but how it travels and how long it takes to reach a reference point …. Well…. That’s how scientists classify the waves. There are S waves, P waves, and surface waves.

23. Seismic Waves P Waves Some seismic waves are longitudinal waves called P waves, or primary waves. They are called primary waves because they move faster than other seismic waves and so arrive at distant points before other seismic waves. P waves are made up of compressions and rarefactions of rock inside Earth. These waves compress and expand the ground like a spring toy as they move through it. P Waves Some seismic waves are longitudinal waves called P waves, or primary waves. They are called primary waves because they move faster than other seismic waves and so arrive at distant points before other seismic waves. P waves are made up of compressions and rarefactions of rock inside Earth. These waves compress and expand the ground like a spring toy as they move through it.

24. Seismic Waves S Waves Transverse seismic waves are known as S waves, or secondary waves. S waves shake the ground up and down and side to side as they move through it. They cannot travel through liquids. Because part of Earth’s core is liquid, S waves do not travel directly through Earth like P waves. S Waves Transverse seismic waves are known as S waves, or secondary waves. S waves shake the ground up and down and side to side as they move through it. They cannot travel through liquids. Because part of Earth’s core is liquid, S waves do not travel directly through Earth like P waves.

25. Seismic Waves Surface Waves When P waves and S waves reach Earth’s surface, they can create surface waves. A surface wave is a combination of a longitudinal wave and a transverse wave that travels along the surface of a medium. Surface waves produced by earthquakes move more slowly than P waves and S waves. However, they can cause the most severe ground movements. They combine up-and-down and side-to- side motions, making the ground roll like ocean waves. Surface Waves When P waves and S waves reach Earth’s surface, they can create surface waves. A surface wave is a combination of a longitudinal wave and a transverse wave that travels along the surface of a medium. Surface waves produced by earthquakes move more slowly than P waves and S waves. However, they can cause the most severe ground movements. They combine up-and-down and side-to- side motions, making the ground roll like ocean waves.

26. Seismic Waves

27. Seismographs are machines that measure energy released from the ground. Seismographs can help to predict earthquakes as well as find oil, gems, and fossils deep under the Earth’s surface. Seismographs are machines that measure energy released from the ground. Seismographs can help to predict earthquakes as well as find oil, gems, and fossils deep under the Earth’s surface.

28. Review Time!!! Define wave. Describe two types of mechanical waves. Identify parts of a wave. Complete wave speed math problems. Determine various wave interactions. Describe how resonance is used in music. How does a geologist utilize a seismograph? Define wave. Describe two types of mechanical waves. Identify parts of a wave. Complete wave speed math problems. Determine various wave interactions. Describe how resonance is used in music. How does a geologist utilize a seismograph?

29. KLM ENTERPRISES 2012