Two metal spheres have radii $r$ and $2r$ and they emit thermal radiation with maximum intensities at wavelengths $\lambda$ and $2\lambda$ respectively. The respective ratio of the radiant energy emitted by them per second will be .........

Observations of light from three different stars $A, B$,and $C$ show that the intensity of the red color is maximum for star $A$,the intensity of the blue color is maximum for star $B$,and the intensity of the yellow color is maximum for star $C$. Which of the following conclusions can be drawn from these observations?

Two bodies $A$ and $B$ of equal surface area have thermal emissivities of $0.01$ and $0.81$ respectively. The two bodies are radiating energy at the same rate. Maximum energy is radiated from the two bodies $A$ and $B$ at wavelengths $\lambda_A$ and $\lambda_B$ respectively. The difference in these two wavelengths is $1 \mu m$. If the temperature of body $A$ is $5802 \ K$, then the value of $\lambda_B$ is:

According to Wien's displacement law:

Solar radiation emitted by the sun resembles that emitted by a black body at a temperature of $6000\,K$. Maximum intensity is emitted at a wavelength of about $4800\,\mathring{A}$. If the sun was cooled down from $6000\,K$ to $3000\,K$,then the peak intensity would occur at a wavelength of ........ $\mathring{A}$.

$A$ perfect black body has a maximum wavelength $\lambda_m$ at a temperature of $2000 \, K$. What will be its maximum wavelength at a temperature of $3000 \, K$?