Briefly describe the physical processes involved in setting a depth for the photosphere. Think in terms of a specific photon moving outward at some depth within the sun. The solar cycle lasts 22 years. This difference is apparent in the photosphere of the star. This assumes that the star is close to a blackbody emitter of light.
Stars are brighter when they are larger because there is a greater area of star emitting light.
A Red giant star is an old star that has expanded in size. It is much brighter than the original star. Assume that the radius of the star was still increased by a factor of 1000. Please give a numerical estimate of the change. Stars are hot and produce light before they start to burn Hydrogen into Helium using fusion.