Question

The spacing between layers of atoms in KCl crystal is 3.1× 10~-10 m.A beam of x-rays is constructively scattered in first order from the surface of the crystal at an angle of 2.9 degree. The wavelength of x-rays is ?

Answer 1

Pls see the pic

It is a question of bragg's law of diffraction of X rays when X rays are made incident on a particular crystal lattice