Question

A black body is at a temperature of 2880K. The energy of radiation emitted by this object with wave length between 499 nm and 500 nm is U₁, between 999 nm and 1000 nm is U₂ and between 1499 nm and 1500 nm is U₃.

Wein constant b=2.88 x 10⁶nmK. Then

• A. U₁ = 0
• B. U₃ = 0
• C. U₁ = U₂
• D. U₂> U₁

Answer 1

Answer: (D)

U₂> U₁

Answer 2

From wein’s Law $\lambda_{m}T$ constant. Where T is temperature of black body and $\lambda_{m}$ is wavelength corresponding to maximum energy of emission.

Energy distribution of blackbody radiation is given below :

1. $U_{1}$ and $U_{3}$ are not zero because a blackbody emits nearly radiation’s of all wavelengths.

2. Since $U_{1}$ corresponds lower wavelength and $U_{3}$ corresponds higher wavelength and $U_{2}$ corresponds medium wavelength. Hence $U_{2} > U_{1}$.

Hence (4) is correct.