The emissive power of a sphere of area $0.04 \,m^2$ is $0.7 \,kcal \,s^{-1} \,m^{-2}$. The amount of heat radiated in $20 \,s$ is: (in $\,kcal$)

The wavelength of maximum energy released during an atomic explosion was $2.93 \times 10^{-10} \, m$. The maximum temperature attained must be (Wien's constant $b = 2.93 \times 10^{-3} \, mK$).

Two bodies $A$ and $B$ radiate maximum energy with a wavelength difference of $4 \mu m$. The absolute temperature of body $A$ is $3$ times that of body $B$. The wavelength at which body $B$ radiates maximum energy is: (in $\mu m$)

The wavelength of maximum emitted energy $(\lambda_m)$ of a body at $700 \ K$ is $4.08 \ \mu m$. If the temperature of the body is raised to $1400 \ K$,then the value of $\lambda_m$ will be (in $\mu m$)

If the wavelengths of maximum intensity of radiation emitted by the Sun and the Moon are $0.5 \times 10^{-6} \, m$ and $10^{-4} \, m$ respectively,then the ratio of their temperatures is ............

$A$ black body at $200 K$ is found to emit maximum energy at a wavelength of $14 \mu m$. When its temperature is raised to $1000 K$,the wavelength at which maximum energy is emitted is: