Light is a form of energy that travels in waves and allows us to see the world around us.
Light travels in straight lines at incredibly high speeds through transparent materials like air and glass. When light hits an object, it can be absorbed, reflected, or transmitted through the material. This fundamental property of light enables us to see both luminous and non-luminous objects. Luminous objects, like the sun or light bulbs, produce their own light through various energy conversion processes. In contrast, non-luminous objects like books, chairs, or trees can only be seen when light reflects off their surfaces and reaches our eyes.
Understanding light energy conversion is crucial in many applications. During photosynthesis, plants convert light energy into chemical energy to produce food. Solar panels demonstrate light energy to electrical energy conversion, harnessing sunlight to generate electricity. Other examples include phosphorescent materials that absorb light energy and re-emit it slowly, and photochromic lenses that darken when exposed to UV light. Light waves exhibit unique properties like reflection, refraction, and diffraction. When light hits a smooth surface like a mirror, it reflects at the same angle it arrived, following the law of reflection. This principle explains how we can see ourselves in mirrors and why smooth water surfaces can act like mirrors on calm days.
At night, we can see non-luminous objects only when artificial light or moonlight (which is reflected sunlight) illuminates them. Common examples of non-luminous objects include furniture, buildings, and clothing. The moon itself is a perfect example of a non-luminous object that we can see clearly because it reflects sunlight. The distinction between luminous and non-luminous objects is fundamental to understanding how we perceive our environment. While luminous objects like stars, flames, and LED screens generate their own light through various energy transformation processes, non-luminous objects rely entirely on reflected light to be visible to our eyes.
