Question

A black body is at a temperature of $5760 \,K$. The energy of radiation emitted by the body at wavelength $250\,nm$ is $U_1$, at wavelength $500\, nm$ is $U_2$ and that at $1000\,nm$ is $U_3$. Wien's constant, $b = 2.88 \times 10^6 \, nm\,K$. Which of the following is correct ?

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

Answer 1

Answer: (C)

$U_2 > U_1$

Answer 2

Maximum amount of emitted radiation corresponding to $\lambda_m = \frac{b}{T}$
$\lambda_m = \frac{2.88 \times 10^{6} \, nmK}{5760K} = 500 \, nm$
From the graph $U_1 < U_2 > U_3$