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The rate of emission of radiation by a black body at 273 deg C is E. What is its rate of emission of radiation at 0 deg C?

1. E/16
2. E/4
3. E/8
4. 0

Correct answer: E/16

Solution

Since rate is proportional to T⁴ and the absolute temperatures are in ratio 546:273 = 2:1, the rate falls by (1/2)⁴ = 1/16, giving E/16.

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