EARTH 255 Lecture Notes - Lecture 4: Low Frequency, Atomic Mass, Photon
19 Sep 2016
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Document Summary
Young"s slit experiment- demonstrated that light has wave-like properties. The speed of light in a vacuum is always the same c=3*10^5 km/s. We need different apparatus in different regions, but can builds up a composite" spectrum for any object. Radiation from an object that radiates as efficiently as any object can. Ideal radiator is ideal absorber- black when cold. A good approximation for many things, from you to stars. The peak increases in wavelength (redder) as the temperature decreases. The total amount of energy (across the whole em spectrum) increases rapidly as temperature increases. If temperature is a factor of 2 more then it"s emitting 2^4. If the stars are known to be at the same distance and appear the same brightness then what can we say about their sizes. The blue star would be the radius of the red. Half the wave length, has to be smaller by a factor of 4.
