Visible light, like all electromagnetic waves, exhibits wave particle duality. It can be viewed as both a wave (exhibiting phenomena such as refraction, reflection, interference, and diffraction) and a particle flow composed of photons (exhibiting quantum properties such as photoelectric effects).
The generation of visible light
Visible light is mainly generated through the luminescence process of matter, including thermal radiation luminescence (such as the sun and light bulbs) and non thermal radiation luminescence (such as fluorescent lamps and LEDs). When a substance is heated to a certain degree, the energy levels of its internal electrons undergo transitions, and the released energy may be radiated in the form of visible light. Non thermal radiation luminescence involves specific physical or chemical processes that cause electrons to transition between different energy levels, releasing visible light.
Visible light is a part of the electromagnetic spectrum that the human eye can perceive, with a wavelength range of approximately 380 nanometers (nm) to 740 nanometers. Electromagnetic waves within this range can be perceived by the human retina and processed into the colors we see through the visual system. Visible light of different wavelengths represents different colors, ranging from shorter wavelengths of purple to longer wavelengths of red, including blue, cyan, green, yellow, and orange in between.
Visible light plays an extremely important role in our lives and technology. Some of the main applications include:
Lighting: From traditional incandescent bulbs to modern LED lights, visible light is used to illuminate our living spaces.
Communication: Fiber optic communication utilizes visible light or near-infrared light to transmit data, providing high-speed network connectivity.
Medical: The use of specific wavelengths of visible light in medical imaging (such as endoscopy) and therapy (such as photodynamic therapy).
Scientific research: By analyzing the absorption and emission characteristics of substances towards visible light, the structure and properties of substances can be studied.
Art and Entertainment: Creating visual art and film works using the color and intensity of visible light.
Visible Light and Human Vision
The human visual system has different sensitivities to different wavelengths of visible light, with the highest sensitivity to green light, which is related to the adaptation of humans to the natural environment during the process of evolution. The cone cells in the human eye are sensitive to color and can be divided into three types, with red, green, and blue light being the most sensitive. By combining these three basic colors in different ways, the human eye can perceive a rich world of colors.
In short, visible light is not only a fundamental phenomenon in nature, but also an important foundation for human civilization and technological development.