Path difference causes destructive interference

Steps:

• Identify the two slits as coherent sources emitting wavefronts.
• Trace paths from each slit to the point, calculating path length difference (ΔL).
• For destructive interference, ΔL = (n + 1/2)λ, where n is integer and λ is wavelength.
• Locate point where this condition holds, indicated by opposing wavefront phases.

Why C is correct:

• At C, path difference equals λ/2, satisfying the condition for complete destructive interference per wave superposition principle.

Why the others are wrong:

• A: Path difference is 0 or mλ, causing constructive interference (maximum).
• B: Position aligns with even multiple of λ/2, resulting in partial or no interference minimum.
• D: Path difference is mλ, leading to constructive interference (maximum).

Final answer: C