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Question
The top of insulated cylindrical container is covered by a disc having emissivity 0.6 and thickness 1 cm. The temperature is maintained by circulating oil as shown in figure. If temperature of upper surface of disc is 127°C and temperature of surrounding is 27°C, then the radiation loss to the surroundings will be (Take 
- 595 J/m2 ' sec
- 595 cal/m2 ' sec
- 991.0 J/m2 ' sec
- 440 J/m2 ' sec
The correct answer is: 595 cal/m2 ´ sec
Rate of heat loss per unit area due to radiation i.e. emissive power 
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