In Young's double slit experiment, how many maximas can be obtained on a screen (including the central maximum) on both sides of the central fringe if `lambda=2000 Å` and `d= 7000 Å` ?

Options

A. 12
B. 7
C. 18
D. 4

Answer

B

Explanation

For maximum intensity on the screen,
`dsintheta= nlambda`
`implies sintheta= (nlambda)/(d)= (n(2000))/(7000) implies sintheta= (n)/(3.5)` as `(sintheta)_("max")= 1`
So, n=0,1,2,3 only
Only seven maximas can be obtained.