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Light and Electromagnetic Energy. The Particle-like nature of light. Light travels in “packets” called Photons. The Wave-like nature of light. Wavelength, l. c = l f. f = frequency, # per second (Hz) c= the speed of light, 300,000 km/s. The Electromagnetic Spectrum.
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Wavelength, l c =lf f = frequency, # per second (Hz) c= the speed of light, 300,000 km/s
The Electromagnetic Spectrum
1 nm = 1 nanometer = 10-9 meters Microwaves Orange Blue Green Yellow violet Red
Planck’s Law Energy of a photon = hc/l h = Planck’s constant c = speed of light l = wavelength
The main purposes of a Telescope: 1. Gather Light 2. Increase Resolution 3. Magnify the image
Two main types of Optical Telescopes: Refracting - uses a lens to bend light Reflecting - uses a mirror
Advantages: Above the atmosphere -> no “seeing” effects -> no absorption -> weather-proof -> it’s always nighttime!
The Very Large Array, New Mexico Interferometry
Astronomical Detectors - The Human Eye - Photographs (1840) - CCD’s (1980)