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Wave Interactions. Pgs. 14 - 19. Reflection. When a wave bounces back after striking a barrier is called reflection. Water, sound and light can all be reflected. An echo is the name of a reflected sound wave. Reflected sunlight allows us to see the moon at night. Refraction.
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Wave Interactions Pgs. 14 - 19
Reflection • When a wave bounces back after striking a barrier is called reflection. • Water, sound and light can all be reflected. • An echo is the name of a reflected sound wave. • Reflected sunlight allows us to see the moon at night.
Refraction • The bending of a wave as it passes at an angle from one medium to another is called refraction. • The speed of the wave varies depending on the medium it is in. • The change of a medium changes the speed of the wave and allows it to bend.
Diffraction • The bending of waves around a barrier or through an opening is called diffraction. • The size of the barrier and wavelength of the wave determine the amount of diffraction.
Interference • The result of two or more waves overlapping is called interference. • Waves can overlap because waves are energy and not matter.
Types of Interference • Constructive interference occurs when the crests of one wave overlap the crest of another and increases the amplitude at the point of interference. • Destructive interference occurs when the crest of one wave and the trough of another overlap and result in a smaller amplitude.
Interference and Standing Waves • Interference can cause a standing wave. • A wave that forms a stationary pattern in which portions of the wave are at rest due to destructive interference while others have a larger amplitude is called a standing wave. • The wave looks to be standing still.
Resonance • Frequencies that produce standing waves are called resonant frequencies. • When an object vibrates at or near resonant frequency of a second object it causes the second object to vibrate. • This is resonance. • A resonating object absorbs energy from the vibrating object. • http://www.youtube.com/watch?v=hiHOqMOJTH4&safety_mode=true&persist_safety_mode=1&safe=active
The Tacoma Narrows Bridge • This bridge was partially destroyed through resonance. • The wind caused vibrations close to resonant frequencies and the bridge began twisting.
http://www.youtube.com/watch?v=j-zczJXSxnw&safety_mode=true&persist_safety_mode=1&safe=activehttp://www.youtube.com/watch?v=j-zczJXSxnw&safety_mode=true&persist_safety_mode=1&safe=active