Final answer:
Stars produce light based on their heat through thermal radiation, and the primary energy source of stars is nuclear fusion, where light atoms fuse to release energy.
Step-by-step explanation:
The phenomenon where stars produce light based on their heat is known as thermal radiation. This is because stars emit light across a variety of wavelengths, and this emission is closely related to the temperature of the star's surface. Specifically, a star like our sun, with a temperature of approximately 5800 K, primarily emits visible light due to thermal radiation.
However, the primary source of a star's energy is nuclear fusion, the process where nuclei of light atoms, like hydrogen, fuse together to form heavier nuclei, such as helium, releasing a significant amount of energy in the form of light and heat. An example of a quantum of light is called a photon, which is relevant in the discussion of the photoelectric effect, another important concept in physics.