The emissivity of tungsten is 0.400. A tungsten sphere with a radius of 1.65 c m

Question

The emissivity of tungsten is 0.400. A tungsten sphere with a radius of 1.65cm is suspended within a large evacuated enclosure whose walls are at 295K . Part A What power input is required to maintain the sphere at a temperature of 3000K if heat conduction along the supports is negligible? H =   W   The emissivity of tungsten is 0.400. A tungsten sphere with a radius of 1.65cm is suspended within a large evacuated enclosure whose walls are at 295K . Part A What power input is required to maintain the sphere at a temperature of 3000K if heat conduction along the supports is negligible? H =   W   The emissivity of tungsten is 0.400. A tungsten sphere with a radius of 1.65cm is suspended within a large evacuated enclosure whose walls are at 295K . The emissivity of tungsten is 0.400. A tungsten sphere with a radius of 1.65cm is suspended within a large evacuated enclosure whose walls are at 295K . The emissivity of tungsten is 0.400. A tungsten sphere with a radius of 1.65cm is suspended within a large evacuated enclosure whose walls are at 295K . Part A What power input is required to maintain the sphere at a temperature of 3000K if heat conduction along the supports is negligible? H =   W   Part A What power input is required to maintain the sphere at a temperature of 3000K if heat conduction along the supports is negligible? H =   W   Part A What power input is required to maintain the sphere at a temperature of 3000K if heat conduction along the supports is negligible? H =   W   H =   W   H =   W   H =   W  

Explanation / Answer

Apply Stefan-Boltzman's law,

emissive power = e*sigma*(T2^4 - T1^4)

= 0.4*5.67*10^-8*(3000^4 - 297^4)

= 1.837*10^6 W/m^2

Power deneed = 1.837*10^6*4*pi*(1.65*10^-2)^2

= 6285 W<<<<<<<<<<<<-----------Answer

here, I took radius of the sphere 1.65 cm

if radius is 1.65 m

then power required = 6.285*10^7 W

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