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MHT CET 2023 (12 May, Shift 1) · Thermal Radiation: Black Body, Stefan & Wien

Thermal Radiation: Black Body, Stefan & Wien question from MHT CET 2023 (12 May, Shift 1)

Q80MHT CET 2023 · 12 MAY · SHIFT 1Medium

Thermal Radiation: Black Body, Stefan & Wien

A black sphere has radius ' $R$ ' whose rate of radiation is ' $E$ ' at temperature ' $T$ '. If radius is made $R/3$ and temperature ' $3T$ ', the rate of radiation will be

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Answer: (d)

Radiated power $P = \sigma (4\pi R^2) T^4$ , so $P \propto R^2 T^4$ .
$\frac{P'}{E} = \left(\frac{1}{3}\right)^2 (3)^4 = \frac{81}{9} = 9$
So the answer is (d) $9E$ .

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