Q. For the constructive interference the path difference between the two interfering waves must be equal to
A) $(2n + 1)\lambda$
B) $2n\pi$
C) $n\lambda$
D) $(2n + 1)\frac{\lambda}{2}$
Explanation
(c) Phase difference,
$\mathrm{\Delta}\phi = \frac{2\pi}{\lambda}\mathrm{\Delta}x$
In a constructive interference,
$\mathrm{\Delta}\phi = 2n\pi$
Where $n = 0,\ 1,\ 2,\ 3,\ \ldots\ldots$
$\therefore 2n\pi = \frac{2\pi}{\lambda}\mathrm{\Delta}x$
Or $\mathrm{\Delta}x = n\lambda$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.