Glossary term: Luz
Description: A luz é uma radiação eletromagnética. No uso comum, o termo “luz” refere-se, normalmente, à radiação eletromagnética cujo comprimento de onda pode ser percebido a olho nu. O comprimento de onda da luz visível aos seres humanos situa-se, de maneira geral, na faixa de 380 a 750 nanômetros (nm), embora a maioria das pessoas tenha pouquíssima sensibilidade à luz com comprimentos de onda inferiores a 400 nm. Essa é uma parte restrita do espectro eletromagnético, que abrange uma ampla gama de comprimentos de onda, desde os raios gama (os mais curtos) até as ondas de rádio (as mais longas). De maneira mais ampla, o termo “luz” é, às vezes, aplicado a qualquer radiação eletromagnética.
As propriedades básicas da luz são intensidade, direção de propagação, frequência, espectro e polarização. Sua velocidade no vácuo é definida como exatamente 299.792.458 metros por segundo, e essa é uma das constantes fundamentais da natureza. A cor da luz depende de seu comprimento de onda. A luz violeta tem o comprimento de onda mais curto no espectro visível; a vermelha, o mais longo. A luz tem múltiplas fontes, naturais e artificiais; o Sol é a principal fonte de luz da Terra. A luz é emitida e absorvida em pequenos “pacotes” chamados fótons, que possuem propriedades tanto de ondas quanto de partículas. Esse último fenômeno é chamado de dualidade onda-partícula.
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Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher The translation of this term and its definition is still awaiting approval
The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".
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Light Dispersion by a Triangular Prism
Caption: This photograph shows a prism splitting a beam of white light into its component colors — a beautiful demonstration of optics, the branch of physics that studies how light behaves and interacts with materials. When white light enters the prism, different wavelengths (colors) bend by different amounts because of a process called refraction. This separation of colors produces a spectrum — similar to a rainbow — revealing that white light is actually made up of many colors combined going from blue, through green and yellow to red.
Understanding optics helps scientists and engineers design lenses, microscopes, telescopes, cameras, and many other tools that shape and control light for practical use. The way the prism disperses light into a spectrum is the same principle that makes rainbows form in the sky when sunlight passes through raindrops.
Credit: Kelvinsong
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