Question

In YDSE, lights of wavelength 600 nm and 480 nm are used. What is the minimum order of bright fringe of 480 nm coincides with bright fringe of 600 nm.

(1) 8

(2) 7

(3) 6

(4) 5

Answer 1

Correct option is : (4) 5

For 480 nm \(w_1 = \frac{480D}{d}\)

For 600 nm = \(w_2 = \frac{600D}{d}\)

 So, 5^th order of 480 nm natcher

Clearly \(5 \Delta w_1 = 4\Delta w_2\)