An equation used to deduce the crystal structure of a material using data obtained from x-rays directed at its surface. The conditions under which a crystal will reflect a beam of x-rays with maximum intensity is:
nλ = 2dsinθ
where θ is the angle of incidence and reflection (Bragg angle) that the x-rays make with the crystal planes, n is a small integer, λ is the wavelength of the x-rays, and d is the distance between the crystal planes. The equation is named for the British physicist Sir William Lawrence Bragg (1890–1971).