Question 365: Properties of Matter

Question

A black body at 227oC radiates heat at the rate of 7 cals/cm2s. At a temperature of 727oC, the rate of heat radiated in the same units will be

Accepted Answer

Rate of heat radiated at (227 + 273) K = 7 cals/(cm
2
s)
Let rate of heat radiated at (727 + 273) K = x cals/(cm
2
s)
By StefanÃ¢ÂÂs law, 7 $$ \propto $$ (500)
4
and x $$ \propto $$ (1000)
4
$$ 	herefore $$ $${x \over 7} = {2^4} \Rightarrow x = 7 	imes {2^4} = 112\,$$ cals/(cm
2
s)

Answer

50

Answer

112

Answer

80

Answer

60

Properties of Matter

A black body at 227oC radiates heat at the rate of 7 cals/cm2s. At a temperature of 727oC, the rate of heat radiated in the same units will be

Choose the correct answer: