What are primary and secondary sources of light? Answer briefly.

Primary sources of light are objects or phenomena that produce light energy directly. They generate and emit light without requiring external illumination. Examples of primary sources of light include the Sun, stars, flames, and incandescent light bulbs.

Secondary sources of light, on the other hand, do not produce light themselves but rather reflect or emit light from a primary source. They rely on the illumination of primary sources to be visible. Examples of secondary sources of light include the Moon, planets, objects illuminated by electric lights, and reflective surfaces such as mirrors.

In summary, primary sources generate light energy, while secondary sources either reflect or emit light that originated from primary sources.