# Chs. 17 & 18 - Waves III. Wave Behaviors Reflection Refraction

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Chs. 17 & 18 - Waves III. Wave Behaviors Reflection Refraction
Diffraction Interference

A. Reflection Reflection when a wave strikes an object and bounces off
Normal Reflection when a wave strikes an object and bounces off incident beam reflected beam

A. Reflection Inversion
A transverse wave traveling to a fixed end or colliding with a denser medium will flip on its way back

A. Reflection Reflecting light in a mirror A type of transverse wave

Ultrasound Medical Imaging “Sound Navigation Ranging”
A. Reflection Ultrasonic waves Ultrasound Medical Imaging SONAR “Sound Navigation Ranging”

Anechoic chamber - designed to eliminate reverberation.
A. Reflection Reverberation echo effect produced by the reflection of sound Anechoic chamber - designed to eliminate reverberation.

B. Refraction Refraction
bending of waves when passing from one medium to another caused by a change in speed slower (more dense)  light bends toward the normal SLOWER FASTER faster (less dense)  light bends away from the normal

B. Refraction Surface waves (ocean waves)
Do not travel throughout the entire medium Refracted as the water depth changes Bends toward the shore

B. Refraction Refraction of light depends on…
speed of light in the medium wavelength of the light - shorter wavelengths (blue) bend more

B. Refraction Example: View explanation.

B. Refraction Example: The “broken” pencil

C. Diffraction Diffraction bending of waves around a barrier
Smaller opening = more diffraction

C. Diffraction longer wavelengths (red, for light) bend more, especially when the opening is small - opposite of refraction

D. Interference Interference – occurs when 2 or more waves overlap
constructive interference  2 or more waves combine to produce a wave with larger displacement Constructive - louder

D. Interference destructive interference  2 or more waves combine to produce a wave with smaller displacement Destructive - softer

D. Interference For light – brighter portions show constructive interference, darker show destructive interference

E. Cool Applications! Fiber Optics Total Internal Reflection
when all light is reflected back into the denser medium

E. Cool Applications! The “Broken Pencil” refraction
View animation and explanation of the “Broken Pencil.”

E. Cool Applications! Rainbows refraction-reflection-refraction

E. Cool Applications! Diffraction Gratings
glass or plastic made up of many tiny parallel slits may also be reflective spectroscopes, reflective rainbow stickers, CD surfaces

E. Cool Applications! Thin Films - Bubbles & Oil Slicks
interference results from double reflection

E. Cool Applications! Blue Sky & Red Sunsets
Molecules in atmosphere scatter light rays. NOON less atmosphere less scattering blue sky, yellow sun Shorter wavelengths (blue, violet) are scattered more easily. SUNSET more atmosphere more scattering orange-red sky & sun

E. Cool Applications! Resonance special case of forced vibration
object is induced to vibrate at its natural frequency

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