Question

Select One Correct Option from the following: In a Young’s double slit experiment, 12 fringes are observed to be formed in a certain segment of the screen when light of wavelength 600 nm is used. If the wavelength of the light is changed to 400 nm, number of fringes observed in the same segment of the screen is given by
(A) 12
(B) 18
(C) 24
(D) 30.

Answer 1

Fringe Width -

\beta = \frac{\lambda D}{d}

 

- wherein

\beta = y_{n+1}-y_{n}

y_{n+1}= Distance of\left ( n+1 \right )^{th}

Maxima= \left ( n+1 \right )\frac{\lambda D}{d}

y_{n}=Distance of n^{th}

maxima = \frac{n\lambda D}{d}

 

Fringe width \propto \lambda  

when we reduce wavelength to half, fringe width also become half . Hence double fringe can be accommodated in the same thickness.

Total number of fringes = 24