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”

A. Reflection RADAR Radio detection and 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