10-2.Heat Transfer question bank (Physics)

The power radiated by a black body is $P$ and it radiates maximum energy around the wavelength $\lambda_0$. Now the temperature of the black body is changed so that it radiates maximum energy around wavelength $\left(\frac{\lambda_0}{2}\right)$. The power radiated by it will now increase by a factor of

Two black spheres '$P$' and '$Q$' have radii in the ratio $3:2$. The wavelengths of maximum intensity radiation are in the ratio $3:4$ respectively. The ratio of radiated power by '$P$' to '$Q$' is (in $/9$)