A coherent light source of wavelength 600 nm falls on two sl

A coherent light source of wavelength 600 nm falls on two slits separated by a d = 0.2 mm. The interference pattern is observed on a screen 1.5 m away from the slits. The first bright fringe is observed at distance y = 1.2 cm away from the center of the screen. What is the path difference delta for the two slits at location y? 125 mu m 1.6 mu m 1.6 mu m 1.25 mm What is the highest order maximum for wavelength 450 nm that can be obtained with a grating with 600 lines per mm? 3 4 6 7

Solution

17. Path difference = d sin = d.y/D = 0.2×1.2/150 = 0.0016 mm = 1.6 m.

Correct option (b).

18. d sin = m

Given, d=1/N = 1/600 mm, = 450 nm, sin = 1.2/150 = 0.008

Highest value of sin = 1

So, the highest value of m = d/= 10⁶/(600×450) = 3.7 4

Correct option (b).