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MHT CET 2023 (10 May, Shift 1) · Thermal Radiation: Black Body, Stefan & Wien

Thermal Radiation: Black Body, Stefan & Wien question from MHT CET 2023 (10 May, Shift 1)

Q84MHT CET 2023 · 10 MAY · SHIFT 1Medium

Thermal Radiation: Black Body, Stefan & Wien

A black body radiates maximum energy at wavelength ' $\lambda$ ' and its emissive power is $E$ . Now due to change in temperature of that body, it radiates maximum energy at wavelength $\frac{2\lambda}{3}$ . At that temperature emissive power is

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Answer: (b)

Wien's law: $\lambda_m T = b$ , so $T \propto \frac{1}{\lambda_m}$ .
$\lambda_m' = \frac{2\lambda}{3} \Rightarrow T' = \frac{3}{2}T$
Stefan's law: $E \propto T^4 \Rightarrow E' = \left(\frac{3}{2}\right)^4 E = \frac{81}{16}E$
So the answer is (b) $\frac{81E}{16}$ .

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