If the first minima in Young's double-slit experiment occurs directly in front of one of the slits (distance between slit and screen `D = 12 cm` and distance between slits `d = 5 cm)`, then the wavelength of the radiation used can be

Options

A. 2 cm only
B. 4 cm only
C. `2m,(2)/(3) cm,(2)/(5) cm`
D. `4 cm,(4)/(3) cm,(4)/(5) cm`

Answer

C

Explanation

Path difference `=sqrt(D^(2)+d^(2))-D=1 cm `
Also, `[sqrt(D^(2)+d^(2))-D]=(2n-1) (lambda)/2`
`rArr lambda (2(1))/(2n-1)`
For n =1,2,3....
`lambda =2 cm, 2/3 cm ,2/5 cm.....`
Hence (C)