A black body is at temperature of 5780 K. The energy of radiation emitted by the body at wavelength 300 nm is U₁, at wavelength 500 nm is U₂ and that at 900 nm is U₃ respectively. Wien's constant b = 2.89 × 10⁶ nmK. This shows that (a) U₁ U₂ > U₃ (c) U₁ U₃ (d) U₁ > U₂ < U₃

Answer: (c). Wien's law: λm = b/T = (2.89 × 10⁶)/(5780) = 500 nm. Energy is maximum at 500 nm and falls on either side. So U₂ is the largest: U₁ U₃, answer (c).

A black body is at temperature of 5780 K. The energy of radiation… | MHT CET 2026 (20 Apr, Shift 2)

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Thermal Radiation: Black Body, Stefan & Wien

A black body is at temperature of 5780 K. The energy of radiation emitted by the body at wavelength 300 nm is $U_1$ , at wavelength 500 nm is $U_2$ and that at 900 nm is $U_3$ respectively. Wien's constant $b = 2.89 \times 10^{6}$ nmK. This shows that

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Answer: (c)

Wien's law: $\lambda_m = \frac{b}{T} = \frac{2.89 \times 10^6}{5780} = 500\text{ nm}$ .
Energy is maximum at 500 nm and falls on either side.
So $U_2$ is the largest: $U_1 < U_2 > U_3$ , answer (c).

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