During a welding operation, thermal power of 2500 W is incident normally on a metallic surface. As shown in the figure below (figure is NOT to scale), the heated area is circular. Out of the incident power, $85 \%$ of the power is absorbed within a circle of radius 5 mm while $65 \%$ is absorbed within an inner concentric circle of radius 3 mm . The power density in the shaded area is __________ $\mathrm{Wmm}^{-2}$ (rounded off to 2 decimal places).
Wien’s law is stated as follows: λmT = C, where C is 2898 μm.K and λm is the wavelength at which the emissive power of a black body is maximum for a given temperature T. The spectral hemispherical emissivity (ελ) of a surface is shown in the figure below (1 Å = 10-10 m). The temperature at which the total hemispherical emissivity will be highest is K (round off to the nearest integer).
A flat plate made of cast iron is exposed to a solar flux of 600 W/m2 at an ambient temperature of 25 °C. Assume that the entire solar flux is absorbed by the plate. Cast iron has a low-temperature absorptivity of 0.21. Use Stefan-Boltzmann constant = 5.669 × 10-8 W/m2-K4. Neglect all other modes of heat transfer except radiation. Under the aforementioned conditions, the radiation equilibrium temperature of the plate is __________ °C (round off to the nearest integer).