If the temperature of a body is increased from $-73^{\circ}C$ to $327^{\circ}C$,the ratio of its emissive power will be ...

Two spheres $P$ and $Q$ have the same emissivity and radii $8 \ cm$ and $2 \ cm$ respectively. They are maintained at temperatures $127^{\circ}C$ and $527^{\circ}C$ respectively. Find the ratio of the radiant energy emitted by $P$ to that by $Q$.

$A$ spherical black body with a radius of $24\;cm$ radiates $440\;W$ power at $500\;K$. If the radius were halved and the temperature doubled,the power radiated in watt would be

Two spherical black bodies of radii $R_1$ and $R_2$ and with surface temperatures $T_1$ and $T_2$ respectively radiate the same power. The ratio of $R_1$ to $R_2$ will be

If the radius of a star is $R$ and it acts as a black body,what would be the temperature of the star,in which the rate of energy production is $Q$? ($\sigma$ stands for Stefan's constant)

Suppose the sun expands so that its radius becomes $100$ times its present radius and its surface temperature becomes half of its present value. The total energy emitted by it then will increase by a factor of