Light

Light is a form of electromagnetic radiation that allows us to see the world around us. The human eye can detect only a small part of the electromagnetic spectrum, called visible light, while other forms such as infrared, ultraviolet, X-rays and radio waves are invisible to us. In a vacuum, light travels at about 299,792 kilometres per second, making it the fastest known phenomenon in the Universe.

Light behaves both as a wave and as tiny packets of energy called photons, a property explained by quantum physics. When light reaches a material, it may be reflected, absorbed, transmitted or refracted, depending on the properties of the substance. These interactions explain everyday phenomena such as mirrors, shadows, lenses, rainbows and the colors we perceive.

The Sun is Earth's main natural source of light and provides the energy that supports nearly all life through photosynthesis. Humans also produce light using technologies such as candles, incandescent bulbs, fluorescent lamps, LEDs and lasers. Studying light has led to major scientific and technological advances, including microscopes, telescopes, cameras, fiber-optic communication and medical imaging devices.

Light also plays an essential role in astronomy because it carries information across vast distances, allowing scientists to study stars, galaxies and planets. Understanding how light behaves helps explain many natural phenomena and continues to drive discoveries in physics, medicine, communications and space exploration.