Please be Seated Making Waves Physics is Phun

Please be Seated

Making Waves Physics is Phun January 2007

View this Power. Point program Programs for Pre-College Students

Bell in Vacuum Experiment

Transverse Waves

c=fl c = speed of light f = frequency l = wavelength

Speed of Light (in a vacuum) c = 300, 000 m/s 8 = 3 x 10 m/s

Longitudinal Waves

s=fl s = speed of sound f = frequency l = wavelength

Speed of Sound s = 331. 45 m/s ~1087 ft/s o at 0 C s = depends on temperature but not on pressure

The “Sonic” Spectrum Infrasound: < 20 Hz Sound: 20 Hz – 20, 000 Hz (20 k. Hz) Ultrasound: > 20 k. Hz (~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 Ball Moving Cars, etc. • Light Spectra 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 pattern Moire figure model

Bose Quiet. Comfort 2 Noise 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 End See you next time! We are on the web at http: //www. physics. umd. edu/lecdem/ Animated Gifs compliments of bellsnwhistles. com