Question

A black body is at a temperature of $2880K$. The energy of radiation emitted by this object with wavelength between $499$nm and $500$nm is $U_1$, between 999nm and 1000nm is $U_2$ and between $1499$nm and $1500$ nm is $U_3$. The Wein constant is $b=2.88\times {10}^{6}nm$K.

• A. $U_1=0$
• B. $U_3=0$
• C. $U_1>U_2$
• D. $U_2>U_1$

Answer 1

The correct option is D $U_2>U_1$

We know that:

${\lambda }_{max}T=2.88\times {10}^6$
${\lambda }_{max}=\frac{2.88\times {10}^{6}nmK}{2880K}$

The black body radiates maximum energy around ${\lambda }_{max}$
Therefore, $U_2$ is greater than $U_1$ and $U_3$.
Also, energy is radiated at all wavelengths.
$\Rightarrow U_1,U_2\ne 0$