The area of a hole of heat furnace is 10-4 m2. It radiates 1.58×105 calories of heat per hour. If the emissivity of the furnace is 0.80, then its temperature is
(a) 1500 K            (b) 2000 K
(c) 2500 K            (d) 3000 K

(c) According to Stefen’s law E=σεAT4

1.58×105××4.260×60=5.6×10-8×10-4×0.8×T4T2500 K

Difficulty Level:

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