9. Bragg law – diffraction of X-rays on crystals, derivation of the formula (3p.)

Question 1

diffraction of X-rays on crystals

Answer 1

X-rays are electromagnetic radiation with wavelengths of the order of 0.1nm.
For such small wavelengths, a standard optical diffraction grating cannot be used.
It was discovered that a crystalline solid might form a natural three-dimensional diffraction grating for X-rays.
An X-ray, which reflects from the surface of a substance has traveled less distance than an X-ray which reflects from a plane of atoms inside the crystal.
The penetrating X-ray travels down to the internal layer, reflects, and travels back over the same distance before being back at the surface.

Question 2

derivation of the formula (Bragg law)

Answer 2

Bragg’s law gives the simple condition under which a diffracted beam can be observed.
𝟐𝒅 𝐬𝐢𝐧 𝜽 = 𝒎𝝀 ; 𝒎 = 𝟏 , 𝟐 , 𝟑 …