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Unformatted text preview: MAE 118A Prof. Tynan Quiz 3 Closed books; closed notes; no electronic devices permitted. Visible light with intensity Ivis (W/m2) passes through a perfectly transmitting window. No visible light is reflected from the window surface. This light is then perfectly absorbed at a surface as shown in the schematic above. This surface warms and emits an infra‐red (IR) radiation flux ES (W/m2). This IR radiation passes back through the window which has a finite IR transmission coefficient, <1. A fraction (1‐ ) of the IR radiation is absorbed by the window which then also warms. The warmed window then re‐emits this radiation with a flux Ew (W/m2) of which half is emitted to space (at a temperature of 0 deg K) and half is emitted back towards the surface. a. Write an expression for the absorbed power flux, A, which the window receives in terms of Es. b. Write an expression for the surface emission, Es. c. Write an expression for the window emission, Ew. d. Solve the two equations from parts b and c to find Es and Ew in terms of I and . e. Find the surface temperature and window temperature. Hint: the emitted flux is related to the temperature by the Stefan‐Boltzmann law E=T4. ...
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This note was uploaded on 02/03/2010 for the course MAE MAE118A taught by Professor Kowsikbodi during the Fall '09 term at UCSD.
- Fall '09