Light

Light is electromagnetic radiation visible to the human eye, occupying wavelengths between approximately 380 and 700 nanometers. It represents a fundamental phenomenon in physics and plays a central role in understanding the universe. Light exhibits wave-particle duality, behaving as both a wave and a particle (photon) depending on the experimental context. This duality was a key discovery in quantum mechanics and remains essential to modern physics.

Speed and Properties

Light travels at approximately 299,792 kilometers per second in a vacuum, a constant denoted as c in physics equations. This speed is invariant across all inertial reference frames, forming a cornerstone of Einstein’s theory of special relativity. Light can be characterized by its wavelength, frequency, and amplitude, which determine its color, energy, and intensity respectively.

Interactions with Matter

When light interacts with matter, it can be absorbed, reflected, refracted, or transmitted depending on the material’s properties. These interactions form the basis for optical technologies including lenses, mirrors, and fiber optic communications. The photoelectric effect, where light ejects electrons from a material, provided early evidence for light’s particle nature and earned Einstein the Nobel Prize in Physics.

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