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MHT CET 2026 (19 May, Shift 2) · Thermal Radiation: Black Body, Stefan & Wien

Thermal Radiation: Black Body, Stefan & Wien question from MHT CET 2026 (19 May, Shift 2)

Q31MHT CET 2026 · 19 MAY · SHIFT 2Medium

Thermal Radiation: Black Body, Stefan & Wien

The power radiated by a black body is PP and it radiates maximum energy at wavelength λ0\lambda_0. If the temperature of the black body is now changed so that it radiates maximum energy at wavelength 0.75λ00.75\lambda_0, the power radiated by it becomes nPnP. The value nn is

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Answer: (b)

  1. Wien: T∝1λmT \propto \frac{1}{\lambda_m}, so T′T=λ00.75λ0=43\frac{T'}{T} = \frac{\lambda_0}{0.75\lambda_0} = \frac{4}{3}.
  2. Stefan: P∝T4⇒n=(43)4=25681P \propto T^4 \Rightarrow n = \left(\frac{4}{3}\right)^4 = \frac{256}{81}
  3. So the answer is (b) 25681\frac{256}{81}.
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