The maximum energy in thermal radiation from a source occurs at the wavelength $4000 \mathring A$. The effective temperature of the source is ....... $K$.

The Earth radiates in the infra-red region of the spectrum. The spectrum is correctly given by

$A$ black body has a maximum wavelength $\lambda_{m}$ at a temperature of $2000 \ K$. Its corresponding wavelength at a temperature of $3000 \ K$ will be:

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

The wavelength of maximum energy released during an atomic explosion was $2.93 \times 10^{-10} \ m$. Given that Wien's constant is $b = 2.93 \times 10^{-3} \ m \cdot K$,the maximum temperature attained must be of the order of:

The surface temperature of the stars is determined using: