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The constant A in the Richardson-Dushman equation for tungsten is 60×104Am−2K−2 The work function of tungsten is 4.5 eV. A tungsten cathode having a surface area 2.0×10−5m2 is heated by the heater and the temperature becomes constant. Assuming that the cathode radiates like a blackbody, calculate the saturation current due to thermions. Take stefan constant=6×10−8Wm−2K−4. Assume that the termions take only a small fraction of th heat suplied. |
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Answer» The constant A in the Richardson-Dushman equation for tungsten is 60×104Am−2K−2 The work function of tungsten is 4.5 eV. A tungsten cathode having a surface area 2.0×10−5m2 is heated by the heater and the temperature becomes constant. Assuming that the cathode radiates like a blackbody, calculate the saturation current due to thermions. Take stefan constant=6×10−8Wm−2K−4. Assume that the termions take only a small fraction of th heat suplied. |
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