Suppose a star with radius 8.50 x 10⁸ m has a peak wavelength of 685 nm in the spectrum of its emitted radiation. (a) find the energy of a photon with this wavelength. (b) what is surface temperature of the star? (c) at what rate is energy emitted from the star in the form of radiation? assume the star is a blackbody (e = 1). (d) using the answer to part (a), estimate the rate at which photons leave the surface of the star.

Asteam power plant operates on an ideal reheat rankine cycle between the pressure limits of 15 mpa and 10 kpa. the mass flow rate of steam through the cycle is 12 kg/s. steam enters both stages of the turbine at 500°c. if the moisture content of the steam at the exit of the low-pressure turbine is not to exceed 10 percent, determine (a) the pressure at which reheating takes place, (b) the total rate of heat input in the boiler, and (c) the thermal efficiency of the cycle. also, show the cycle on a t-s diagram with respect to the saturation lines. (2.15 mpa; 45.0 mw; 42.6%)