Q.46. Two sources of light 0.6 mm apart and screen is placed at a distance of 1.2 m from them. A light of wavelength 6000Ao used. Then the phase difference between the two light waves interfering on the screen at a point at a distance 3 mm from central bright band is
A. 6π radian
B. 3π radian
C. 4π radian
D. 5π radian
Answer :- D. 5π radian
Explanation :-
Fringe width:
W = \frac{\lambda D}{d} = \frac{6000 \times 10^{-10} \times 1.2}{0.6 \times 10^{-3}} = 1.2 \, \text{mm}\therefore Number of fringes = \frac{3}{1.2} = 2.5
\therefore Phase difference:
\Delta \phi = 2n\pi = 2 \times 2.5 \pi = 5\pi