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MHT CET 2021 (20 Sep, Shift 2) · Thermal Radiation: Black Body, Stefan & Wien

Thermal Radiation: Black Body, Stefan & Wien question from MHT CET 2021 (20 Sep, Shift 2)

Q95MHT CET 2021 · 20 SEP · SHIFT 2Medium

Thermal Radiation: Black Body, Stefan & Wien

A black rectangular surface of area ' $A$ ' emits energy ' $E$ ' per second at $27^\circ\text{C}$ . If length and breadth is reduced to $(1/3)$ rd of its initial value and temperature is raised to $327^\circ\text{C}$ then energy emitted per second becomes

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Answer: (c)

$E \propto A T^4$ .
Length and breadth become $\frac{1}{3}$ : $A \to \frac{A}{9}$ .
$T: 300\text{ K} \to 600\text{ K}$ , factor $16$ .
$E' = \frac{16E}{9}$ , so the answer is (c).

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