07336 IUPAC Gold Book - Brewster angle 10.1351/goldbook.BT07336 BT07336 current quantity 1 When an unpolarized planar electromagnetic wavefront impinges on a flat dielectric surface, there is a unique angle (\(\theta_{\rm{B}}\)), commonly referred to as Brewster angle, at which the reflected waves are all polarized into a single plane. Expression for Brewster angle: \[\theta_{\rm{B}} = \rm{arctan} \frac{n_{2}}{n_{1}} = \rm{arctan} \left (\frac{\varepsilon_{2}}{\varepsilon_{1}} \right)^{1/2}\] where \(n_{2}\) and \(n_{1}\) are the refractive indices of the receiving surface and the initial medium, respectively, and \(\varepsilon_{2}\) and \(\varepsilon_{1}\) are the relative static permittivities (formerly called dielectric constants). For a randomly polarized beam incident at Brewster angle, the electric fields of the reflected and refracted waves are perpendicular to each other For a wave incident from air on water (\(n = 1.333\)), glass (\(n = 1.515\)), and diamond (\(n = 2.417\)), the Brewster angles are \(53\), \(57\), and \(67.5\ \rm{degrees}\), respectively. angle https://goldbook.iupac.org/terms/view/A00346 diamond https://goldbook.iupac.org/terms/view/D01671 PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 310 (https://doi.org/10.1351/pac200779030293) https://goldbook.iupac.org/terms/view/BT07336/html https://goldbook.iupac.org/terms/view/BT07336/json https://goldbook.iupac.org/terms/view/BT07336/plain Citation: 'Brewster angle' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.BT07336 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-05-15T03:54:28+00:00