Question

Two sources of light of wavelengths 2500 Å and 3500 Å are
used in Young’s double slit expt. simultaneously. Which
orders of fringes of two wavelength patterns coincide?
(a) 3rd order of 1st source and 5th of the 2nd
(b) 7th order of 1st and 5th order of 2nd
(c) 5th order of 1st and 3rd order of 2nd
(d) 5th order of 1st and 7th order of 2nd

Answer 1

Answer:

a

Explanation:

3rd order of 1st source and 5th of the 2nd

Answer 2

Answer:b

Explanation:

As wavelength is inversely proportional to order... As given by formula dsin@= m£

dsin@/m= £

So £1/£2= m2/m1

2500/3500=5/7

So m1= 7 and m2= 5