The eye of a stove top has a total area of 0.0628 m2 and gives off energy at a rate of 8720 W. If we assume the stove top eye to be a perfect blackbody, what would be the temperature of the eye in Kelvin?

The next four questions use this description.  Our Sun has a peak emission wavelength of about 500 nm and a radius of about 700,000 km. Your dark-adapted eye has a pupil diameter of about 7 mm and can detect light intensity down to about 1.5 x 10-11 W/m2.  Assume the emissivity of the Sun is equal to 1. First, given these numbers, what is the surface temperature of the Sun in Kelvin to 3 significant digits? What is the power output of the Sun in moles of watts?  (in other words, take the number of watts and divide it by Avogadro's number) Assuming that all of the Sun's power is given off as 500 nm photons*, how many photons are given off by the Sun every second? Report your answer to the nearest power of 10 (e.g. if you got 7 x 1024, give your answer as 25).

Presents the diagram of the problem, necessary formulas, clearance and numerical solution: The surface of the Sun has a temperature of about 5,800 K. The radius of the Sun is 6.96x108 m. Calculate the total energy radiated by the Sun each second. Assume the emissivity is 0.986.

Imagine a thermometer which is spherical shell of volume 100 cm attached to a long tube with equally spaced marks on it. The volume of the tube between to consequent marks is 0.2 cm. Sphere and tube contain air separated from surronding space by a drop of water. At temperature 5°C this water drop is at the 20-th mark on the tube. What is the temperature in the room where the drop settles at the 50-th mark.