Lecture 1

Lecture 1 - o Does light travel instantaneously? Water...

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Lecture 1- Thursday, January 21, 2010 Light 1. There are many colors of light o Some colors (like white) are composed of different colors o The colors can be split up again into a spectrum Diffraction grating (what you have) Prism Water droplets Rainbow 2. Astronomers do this too o Use diffraction gratings to analyze spectra (spectroscopy) 3. How is red light different to blue light? o What is changing as you go along the spectrum? Answer 1: light behaves like a wave. What varies along the spectrum is the wavelength and frequency of the wave Answer 2: light behaves like particles (photons) What varies along the spectrum is the energy of each photon 4. What is doing the waving? o Electric and magnetic fields are oscillating off themselves 5. The speed of light waves
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Unformatted text preview: o Does light travel instantaneously? Water moves more slowly - you can watch them Sound waves are faster, but still not instant - thunder and lightning o Galileo and Newton both wanted to know this Romer found the answer from the moons of Jupiter Eclipses of moons are early when Jupiter is close and late when it is far away Romer measured about 186,000 miles/second - still very fast Modern experiments give 299,792,458 m/s You can assume 3.0 x 10^8 m/s for this course 6. The Spectrum of "Light" o Electromagnetic spectrum 7. Kirchhoff's Laws o Law 1 Hot opaque body (including gas) produces continuous spectrum o Law 2 Hot transparent gas produces emission lines spectrum...
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