Essential questions What is a wave What is

Essential questions Ø What is a wave? Ø What is a medium? Ø What is the difference between a longitudinal and transverse wave? Ø What are the properties of a wave? Ø What behaviors do all waves have in common? Ø What is the difference between reflection, refraction, and diffraction?

Nature of Waves Ø Wave—any disturbance (movement) that matter or transfers energy through _______ space empty ____. (Mechanical) vibrating Ø Waves move energy by ______ particles _____in a medium. Ø Medium—a substance a wave can travel solid, liquid, or gas through; it can be_________. Ø Ø Characteristics of Waves: Sound waves http: //www. youtube. com/watch? v=8 i 6 h. TU 0 jw-g

Nature of Waves Ø Ø Ø 1. 2. 3. 4. Ø Waves that do NOT need a medium are electromagnetic called _____ waves _____ ___ Examples: 1. _______ Visible light 2. Microwaves 3. x-rays T. V. & radio waves http: //www. youtube. com/watch? v=7 y. P Waves that need a medium to move are called _____ mechanical waves _______ Ex amples: _______ Sound waves _______ Ocean waves Seismic waves (earthquakes)

Types of waves energy by repeated Ø All waves transfer _______________. vibrations Transverse Ø ________waves—particles up-and-down vibrate in an ________motion while the energy moves across. Particles Energy http: //www. youtube. com/watch? v=TZIr 9 mp. ERb. U&NR=1 rope example http: //www. youtube. com/watch? v=g 49 mah. Ye. Ngc slow motion

Longitudinal wave—the particles of the Ø ______ medium vibrate back and forth in the same direction the wave energy is moving. Ø Compression ______ —part of a longitudinal wave where the particles are crowded (pressed) together. RAREFACTION: The part where the particles are spread apart. Particles & Energy

Wave animations Ø http: //www. youtube. com/watch? v=7 c. DAYF TXq 3 E Ø http: //www. youtube. com/watch? v=Js. JOug 4 Sq. L 8

Properties of waves Ø Amplitude—(wave height) distance from the rest position to the crest or trough Ø Large amplitude=more energy crest position trough

Wavelength —the distance from any point on a wave to an identical point on the next wave. (crest to crest, trough to trough, compression to compression, rarefaction to rarefaction) Shorter wavelength=more energy

waves Ø Frequency —the number of _____ second , passing through an area in one _______ Hertz measured in _______ (Hz) 1 Hertz = 1 wave per second 5 waves in 1 second= 5 Hz Higher frequency= higher energy Wave speed— speed at which a wave travels =frequency x wavelength 1 second Low frequency-few waves Per second Higher frequency—more Waves per second

Wave property animations Ø Wave motion: change frequency, wavelength etc…http: //profhorn. aos. wisc. edu/wxwise/kinematics/wavemotion. h tml Ø Characteristics of Waves: Amplitude, Wavelength and Frequency http: //www. youtube. com/watch? v=aif 5 mxf 5 Dt. U

Wave Interactions Reflection —when a wave _______ bounces Ø ______ __ _back _ _____after hitting a barrier it can’t go through. All types of waves can be reflected echo —a reflected sound wave, Example: ______ sonar Light waves reflected off an object allow you to see it. surface

Refraction —the ____ bending of light waves Ø _____ as they pass through from one medium to another at an angle. § When a wave passes from one medium to another, it’s speed and wavelength changes so it _____. bends Examples: White light bends to form a rainbow

Diffraction —the change in direction of a Ø _____ wave as it bends around a barrier or opening Resonance—when two objects vibrate at the same frequency; one object causes ___________. another object to vibrate Ø http: //www. acoustics. salford. ac. uk/schools/teach er/lesson 3/flash/whiteboardcomplete. swf Ø interactive wave disturbance tutorial

§ A resonating object absorbs energy from the vibrating object and begins to vibrate too. The 4 month old bridge collapsed during a windstorm with gusts that reached 68 km/h (42 mph). The catastrophe was attributed to faulty design. Instead of allowing the wind to pass through, the suspended girders caught the wind, causing the bridge to buck and roll. The bucking motion earned the bridge the nickname Galloping Gertie. The stronger the wind blew, the more violently the structure oscillated, until it finally broke apart and crashed into the water. http: //www. youtube. com/watch? v=Cs. KKDLKYs. VU http: //www. wsdot. wa. gov/tnbhistory/connections 3. htm

Label the wave parts 1 second 0 seconds Type of wave: Longitudinal Frequency: 3 Hertz ____ Type of wave: Transverse Frequency: ____ 3. 5 Hertz amplitude __________ wavelength ______

Waves Transverse Longitudinal Energy Medium Frequency Amplitude Wave speed DRAW THIS CHART IN YOUR NOTEBOOK http: //sci-culture. com/advancedpoll/GCSE/sine%20 wave%20 simulator. html wave simulator