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Unformatted text preview: Announcements • Reading for Monday: 5.1 – 5.5 Today: Back to our discussion about Photons! All these fifty years of conscious brooding have brought me no nearer to the answer to the question, ' What are light quanta ?' Nowadays every Tom, Dick and Harry thinks he knows it, but he is mistaken! ( Albert Einstein , 1954) Recap: Intensity ∝ E max 2 but does not depend on frequency! X X vs. Common confusion: Interference was definitive test that light is a wave! “Why do higher frequency gamma rays carry more energy ( hf ) than lower frequency radio waves, but frequency has nothing to do with intensity, what gives?” Do not confuse the energy carried by a beam of light with the energy of a single quantum particle of light! X Electromagnetic Waves and Photons are describing the same thing! Need to have a model where these views/perspectives all fit together and are consistent with each other! 1. Light, Radio waves, X-rays are all electromagnetic waves! 2. The electromagnetic wave is made up from lots of photons. 3. Photons could be thought of as mini E/M wave segments (each has a specific energy hf and a wavelength c/f ) This picture can help explain wave view and particle view. “Particle” = little chunk of the electromagnetic wave. Energy of photon ( hf ) is in its oscillating E and B fields. (Sometimes it also helps to think of a photon as a tiny particle/energy packet)....
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