Two stars emit maximum radiation of wavelength $3600\,\mathop A\limits^o $  and $4800\,\mathop A\limits^o $  respectively. The ratio of their temperatures is

If the temperature of a black body increases from $7\,^oC$ to $287\,^oC$ then the rate of energy radiation increases by

The ratio of thermal conductivity of two rods of different materials is $5 : 4$. The two rods of same area and same thermal resistance will have lengths is the ratio

Solar radiation emitted by the sun resembles that emitted by a black body at a temperature of $6000\, K$. Maximum intensity is emitted at a wavelength of about $4800\,\mathop A\limits^o $. If the sun was cooled down from $6000\, K$ to $3000\, K$, then the peak intensity would occur at a wavelength of ……… $\mathop A\limits^o $

Two bodies $P$ and $Q$ have thermal emissivities of $\varepsilon_P$ and $\varepsilon_Q$ respectively. Surface areas of these bodies are same and the total radiant power is also emitted at the same rate. If temperature of $P$ is $\theta_P$ kelvin then temperature of $Q$ i.e. $\theta_Q$ is