Question

In Young's double slit experiment, wavelength of light is $6000\mathring{A}$. Then the phase difference between the light waves reaching the third bright fringe from the central fringe will be:

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

Answer 1

The correct option is D $6\pi$

Given,

$\lambda =6000A^0$

$n=3$

Path difference,

$\Delta x=n\lambda =3\lambda$

Phase difference,

$\varphi =\frac{2\pi }{\lambda }\times \Delta x$

$\varphi =\frac{2\pi }{\lambda }\times 3\lambda$

$\varphi =6\pi$

The correct option is D.