EVSC 1450 Lecture Notes - Lecture 4: Photon, False Color, Electric Light
31 Aug 2016
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If you know temperature, you know internal energy. Energy moves from place to place at t arate. Energy (j) vs power (j/s or w) Characteristic wavelength determines how photons interact with the world. Wavelength and total power vary with temperature. For any given wavelength, power increases with temperature. Most objects on earth are 200 to 300* k, so we don"t see the photons flowing out of the most objects. Sun and lava are not blackbody, but most other things are. While not too many things glow in the visible, we can see the invisible with equipment. If you know the wavelength, you know the temperature and vice versa. Remember, peak shifts to shorter wavelengths following wien"s displacement law. P = e/t (not t (temperature), but t=time) Units are: p= w, a = m2, w/m2. = constant =5. 67 * 10-8 w/m2/k4. See, t4 has units of k4, it all cancels to w/m2. Plug in sigma, plug in temperature, out comes power.
