Question

In Young's double slit experiment, the phase difference between the waves reaching the central fringe and third bright fringe will be

• A. zero
• B. $2\pi$
• C. $4\pi$
• D. $6\pi$

Answer 1

The correct option is D $6\pi$

Path difference between the waves reaching the central fringe and 3rd bright fringe is equal to $3\lambda$.

Phase difference $\delta =\frac{2\pi }{\lambda }\Delta x=\frac{2\pi }{\lambda }\times 3\lambda$

$⟹\delta =6\pi$