5. The rate of dissipation of heat ...
Question

# 5. The rate of dissipation of heat by a black body at temperature T is Q. What will be the rate of dissipation of heat by another body at temperature 2T and emissivity 0.25 ? (1) 16 Q (2) 4Q (3) 8Q (4) 4.50

JEE/Engineering Exams
Physics
Solution
183
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[ begin{array}{l} text { Qe } e^{pi^{4}} frac{Q_{1}}{Q_{2}}=frac{operatorname{li}_{1}^{4}}{ln ^{5} T_{2}^{4}}=frac{1(T)^{4}}{frac{1}{4}(2 T)^{4}}=frac{T^{4}}{4 T^{4}} therefore Q_{2}=4 Q_{1} end{array} ] Ophon ( (therefore D) ) 4 ( Q )