If a graph is plotted by taking spectral emissive power along $y$-axis and wavelength along $x$-axis,then the area under the graph above the wavelength axis is ...........

In the figure,the distribution of energy density of the radiation emitted by a black body at a given temperature is shown. The possible temperature of the black body is ....... $K$.

The temperature of a furnace is $2000^\circ C$ and the wavelength of maximum intensity in its spectrum is $4000 \ \mathring{A}$. If the wavelength of maximum intensity is $2000 \ \mathring{A}$, calculate the temperature of the furnace in $^\circ C$.

Two bodies $A$ and $B$ have emissivities $0.01$ and $0.81$ respectively. The outer surface areas of both bodies are the same. Both bodies emit total radiant power at the same rate. The wavelength $\lambda_B$ corresponding to the maximum spectral radiance of $B$ is $1.0 \mu m$. If the temperature of $A$ is $5802 \ K$,calculate the wavelength $\lambda_A$ in $\mu m$. (Note: The original question asked for $\lambda_B$ but provided $\lambda_B$ as $1.0 \mu m$ and asked for $\lambda_A$ based on the context of the solution provided).

State and explain Wien's displacement law.

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