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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This note was uploaded on 03/30/2012 for the course ASTR 1102 taught by Professor Staff during the Spring '08 term at LSU.

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