Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos
Bragg reflection
References
Images
Diagram illustrating Bragg diffraction, showing two waves striking parallel atomic planes at equal incident and reflected angles, with labeled distances and angles to explain constructive interference.
Britannica AI Icon

Bragg reflection

physics
Also known as: Bragg diffraction, Bragg scattering
Written by
The Information Architects of Encyclopaedia Britannica

The Information Architects maintain a master list of the topics included in the corpus of  Encyclopædia Britannica, and create and manage the relationships between them.
The Information Architects of Encyclopaedia Britannica
Last updated

Quick Summary

Diagram illustrating Bragg diffraction, showing two waves striking parallel atomic planes at equal incident and reflected angles, with labeled distances and angles to explain constructive interference.
Bragg diffraction Bragg diffraction. Waves 1 and 2, in phase with each other, glance off atoms A and B of a crystal that has a separation distance d between its atomic, or lattice, planes. The reflected (glancing) angle θ, as shown by experiment, is equal to the incident angle θ. The condition for the two waves to stay in phase after both are reflected is that the path length CBD be a whole number (n) of wavelengths (λ), or nλ. But, from geometry, CB and BD are equal to each other and to the distance d times the sine of the reflected angle θ, or d sin θ. Thus, nλ = 2d sin θ, which is the Bragg law. As may be seen from the diagram, when n = 2, there is only one wavelength along path CB; also, the reflected angle will be smaller than that for, say, n = 3. Waves reflected through an angle corresponding to n = 1 are said to be in the first order of reflection, the angle corresponding to n = 2 is the second order, and so on. For any other angle (corresponding to fractional n), the reflected waves will be out of phase and destructive interference will occur, annihilating them.

Bragg reflection, a concept in physics, describes how crystals reflect X-rays or particle waves. This occurs when the waves are in phase, leading to constructive interference. The Bragg law, formulated by Lawrence Bragg, relates the spacing of atomic planes in crystals (d) to the angle of incidence (\u03b8) and the wavelength (\u03bb) of the radiation. The law is expressed as n\u03bb = 2d sin \u03b8, where n is an integer representing the order of reflection. This phenomenon is crucial for determining crystal structures and measuring wavelengths of X-rays and neutrons.123

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
4 Britannica Sources
  1. Bragg law
  2. Bragg reflection
  3. X-ray diffraction
  4. spectroscopy - X-ray optics

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.