Characteristics of light

Light propagates at a velocity of 300,000 km per second.

Light propagates at an approximate velocity of 300,000 km per second. Remarkably, light can circumnavigate the Earth 7.5 times in just one second. This characteristic of light is employed in several technical applications, including optical communications, which transmit substantial data in a brief duration. Nonetheless, even light, the fastest entity known to humanity, can traverse just 0.3 millimetres in a trillionth of a second (a picosecond) in a vacuum. In recent years, the study of optical phenomena occurring over remarkably brief intervals has become crucial in emerging disciplines of physics, chemistry, biology, and others.
1 millisecond equals 1/1000 of a second, 1 microsecond equals 1/1,000,000 of a second, 1 nanosecond equals 1/1,000,000,000 of a second, and 1 picosecond equals 1/1,000,000,000,000 of a second.

Light-matter interaction

Light exhibits several behaviours upon interaction with objects.
In a vacuum, such as outer space devoid of substance, light propagates in a linear manner. Light exhibits many behaviours when interacting with water, air, and other substances; it is "absorbed," "transmitted," "reflected," and "scattered." When light interacts with matter, a portion of the light is absorbed by the matter and converted into thermal energy. If the substance upon which light impinges is transparent, the light component that remains unabsorbed within the substance is "transmitted" via (b) and emerges on the outside side of the material. If the material's surface is flat, such as a mirror, "reflection" occurs; nevertheless, if the surface is uneven with pits and protrusions, the light "scatters."
The transmitted, reflected, or dispersed light enables our eyes to perceive the colours and forms of objects.