ANS:A - nλ = 2d Sin θ

The condition of diffraction from a crystal is given by: nλ=2dsin(θ) Where:

• n is the order of diffraction (an integer),
• λ is the wavelength of the incident radiation,
• d is the spacing between atomic planes in the crystal lattice, and
• θ is the angle of diffraction.

This equation, known as Bragg's law, describes the constructive interference that occurs when X-rays or other electromagnetic waves are diffracted by a crystal lattice. It relates the wavelength of the incident radiation, the spacing between atomic planes, the angle of incidence, and the order of diffraction.