$A$ black body emits radiation of maximum intensity at wavelength $\lambda$ at temperature $T \ K$. Its corresponding wavelength at temperature $1.5 \ T \ K$ will be

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 $\,kcal$)

$A$ 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

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

The plots of intensity versus wavelength for three black bodies at temperatures $T_1$,$T_2$ and $T_3$ respectively are as shown. Their temperatures are such that

If the temperature of a black body is doubled,the frequency at which the spectral intensity becomes maximum will be