Wien's displacement law expresses the relation between:

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

The black body spectrum of an object $O_1$ is such that its radiant intensity (i.e.,intensity per unit wavelength interval) is maximum at a wavelength of $200\,nm$. Another object $O_2$ has the maximum radiant intensity at $600\,nm$. The ratio of power emitted per unit area by source $O_1$ to that of source $O_2$ is

We consider the radiation emitted by the human body. Which of the following statements is true?

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 $,\mu m$)?

The surface temperature of the sun which has maximum energy emission at $500 \,nm$ is $6000 \,K$. The temperature of a star which has maximum energy emission at $400 \,nm$ will be: (in $\,K$)