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NEET 2002
Exam
NEET
Year
2002
Subject
Physics
Chapter
Thermal Properties of Matter

NEET 2002 · Physics · Thermal Properties of Matter

For a black body at temperature 727^ C , its radiating power is 60...

For a black body at temperature 727∘C727^{\circ} \mathrm{C}, its radiating power is 60 W60 \mathrm{~W} and the temperature of surrounding is 227∘C227^{\circ} \mathrm{C}. If temperature of the black body is changed to 1227∘C1227^{\circ} \mathrm{C}, then its radiating power will be:

Options

  1. A304 W304 \mathrm{~W}
  2. B320 W320 \mathrm{~W}
  3. C240 W240 \mathrm{~W}
  4. D120 W120 \mathrm{~W}

Correct answer

B. 320 W320 \mathrm{~W}

Step-by-step solution

We can use the formula P∝(T4−T04)∴P2P1=(1500)4−(500)4(1000)4−(500)4=5004(34−1)5004(24−1)∴P260=8015⇒P2=320 W\begin{aligned} & P \propto\left(T_4-T_0^4\right) \\ & \therefore \frac{P_2}{P_1}=\frac{(1500)^4-(500)^4}{(1000)^4-(500)^4} \\ & =\frac{500^4\left(3^4-1\right)}{500^4\left(2^4-1\right)} \\ & \therefore \frac{P_2}{60}=\frac{80}{15} \Rightarrow P_2=320 \mathrm{~W} \end{aligned}
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