Please be Seated. Making Waves Physics is Phun January 2007

Pleasebe

Seated

Making Waves

Physics is Phun

January 2007

View this PowerPoint program

Programs for Pre-College Students

Bell in Vacuum Experiment

Transverse Waves

c = f

c = speed of light

f = frequency= wavelength

Speed of Light(in a vacuum)

c = 300,000,000 m/s

= 3 x 108 m/s

Longitudinal Waves

s = f

s = speed of sound

f = frequency= wavelength

Speed of Sounds = 331.45 m/s

~1087 ft/s

at 0o C

s = depends on temperature

but not on pressure

The “Sonic” SpectrumInfrasound:

< 20 Hz

Sound:20 Hz – 20,000 Hz (20kHz)

Ultrasound:> 20 kHz (~1013 Hz maximum)

Light waves:1. are transverse waves.2. do not require a medium.

Sound waves:1. are longitudinal waves.2. require a medium.

Wave Properties I• Superposition

• Hugygens’ Principle

• Doppler Effect

Superposition

Huygens’ Principle

Doppler Effect• Sound

Doppler BallMoving Cars, etc.

• LightSpectra of stars

Fraunhofer Spectrum

Wave Properties II•Diffraction

•Interference

•Reflection

•Refraction

Diffraction

Waves spread out and bend around corners within the same medium.

Highway Sound Barrier

Photograph courtesy of Enterprise Flasher Company

Interference

Two-source interference patternMoire figure model

Bose QuietComfort 2Noise Cancelling Headphones

Light examples

“Iridescence”of peacock feather

Reflection

Refraction

Waves bend due to variation of medium.

Waves at the Beach

Mirage Formation

Water Mirage

Desert Lake

Mirage

Compliments of Robert Greenler

Sunrise over the Ocean

The EndSee you next time!

Animated Gifs compliments of bellsnwhistles.com

We are on the web at http://www.physics.umd.edu/lecdem/