The intensity of radiation emitted by the sun has its maximum value at a wavelength of $510\;nm$ and that emitted by the north star has the maximum value at $350\;nm$. If these stars behave like black bodies,then the ratio of the surface temperature of the sun and north star is

Three black discs $x, y, z$ have radii $1 \ m, 2 \ m$ and $3 \ m$ respectively. The wavelengths corresponding to maximum intensity are $200 \ nm, 300 \ nm$ and $400 \ nm$ respectively. The relation between emissive power $E_x, E_y$ and $E_z$ is:

If the temperature of the sun becomes twice its present temperature,then

The wavelength of the radiation emitted by a black body is $1 \,mm$ and Wien's constant is $3 \times 10^{-3} \,mK$. Then the temperature of the black body will be (in $\,K$)

The maximum wavelength of radiations emitted at $900\,K$ is $4\,\mu m$. What will be the maximum wavelength of radiations emitted at $1200\,K$ (in $,\mu m$)?

Two spherical bodies $A$ (radius $6 \,cm$) and $B$ (radius $18 \,cm$) are at temperatures $T_1$ and $T_2$,respectively. The maximum intensity in the emission spectrum of $A$ is at $500 \,nm$ and in that of $B$ is at $1500 \,nm$. Considering them to be black bodies,what will be the ratio of the rate of total energy radiated by $A$ to that of $B$?