In about five billion years, the Sun will evolve into a red giant. Assume that its surface temperature will decrease to about half its present value of K, while its present radius of m will increase to m, which is the current Earth-Sun distance. Calculate the ratio of the total power emitted by the Sun in its red giant stage to its present power.
The radiant energy from the Sun reaches its maximum at a wavelength of about 0.5 μm. What is the approximate temperature of the Sun’s surface?
The tungsten elements of incandescent light bulbs operate at 700 K. At what frequency does the filament radiate maximum energy?