The path difference between reflections from adjacent planes is 2d sin θ, which leads to the Bragg condition for constructive interference.

Interference is the process where superposition of waves leads to varying intensity at a point; the OCR marks option A.

Path difference is the same: m1·λ1 = m2·λ2 ⇒ λ2 = (3·700 nm)/5 = 420 nm, so option D is correct.

Increasing wavelength increases the diffraction angles (sinθ = nλ/d), so the diffracted images move farther from the central image D.

Blue light has a shorter wavelength than red, so diffraction angles are smaller and bands become narrower and closer together.

Bragg's law (nλ = 2d sin θ) is specifically used with crystal planes to determine X-ray wavelengths, unlike optical double-slit or grating experiments.

X-ray diffraction techniques have been used to study DNA structure, haemoglobin, and general crystal structures, so all listed examples apply.

With d = 1/(4.5×10^5) and nλ = d sinθ, for n=2 and θ=30° we get λ ≈ 5.56×10^-7 m (≈556 nm).

Fringe width β = Dλ/d; equal β and same λ imply D ∝ d, so D ratio equals slit separation ratio 2:3.

Diffraction is the phenomenon where waves bend around obstacles and spread into geometrical shadows.