alleryAt a point where the path difference between two coherent light waves is 3λ/2, the interference is
AConstructive (bright)
BNeither bright nor dark
CDestructive (dark)
DDepends on intensity
Answer & Solution
Correct answer: C. Destructive (dark)
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: syllabus Physics, Ch 10 "Wave Optics", §10.4_
Keep practising Wave Optics
Browse all Wave Optics questions for JEE Advanced, or explore more Physics topics.
Related questions
Polarisation of light is direct experimental evidence that light is a:The resolving power (RP) of a diffraction grating with N slits in the m-th order is:In Young's double-slit experiment, the fringe width β is given by:In Young's experiment, a BRIGHT fringe (constructive interference) requires path differencIn single-slit diffraction, the central maximum is:BREWSTER'S LAW for the polarising angle θ_B relates to the refractive index n as:HUYGENS' PRINCIPLE states that every point on a wavefront acts as a:Light passes from air to glass ($n = 1.5$). Brewster's angle is: