At a point where the path difference between two coherent light waves is 3λ/2, the interference is
A{'text': 'Constructive (bright)', 'label': 'A'}
B{'text': 'Neither bright nor dark', 'label': 'B'}
C{'text': 'Destructive (dark)', 'label': 'C'}
D{'text': 'Depends on intensity', 'label': 'D'}
Answer & Solution
Correct answer: C. {'text': 'Destructive (dark)', 'label': 'C'}
1. Constructive interference: path difference = n λ (n = 0, 1, 2, …).
2. Destructive interference: path difference = (2n + 1) λ / 2.
3. 3λ/2 corresponds to n = 1: (2×1 + 1) λ / 2 = 3λ/2.
4. So this is a dark fringe (destructive interference).
_Source: NCERT Class 12 Physics, Ch 10 "Wave Optics", §10.4_
Related questions
Newton originally supported the corpuscular theory of light. The wave theory was strongly In a Young's double-slit experiment, a thin transparent sheet of thickness t and refractivCoherent sources are those that emit waves ofIf polarised light of intensity I passes through a polariser whose axis makes angle θ withAn unpolarised light of intensity I₀ passes through a polariser. The transmitted intensityWhich of the following phenomena is characteristic ONLY of transverse waves and NOT of lonThe polarising angle (Brewster angle) for glass of refractive index 1.5 isThe width of the central maximum in single-slit diffraction on a screen at distance D is