Question

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 $(\lambda =2000\mathring{A})$?

• A. $12$
• B. $7$
• C. $18$
• D. $4$

Answer 1

Answer: (B)

$7$

Maximum intensity of the screen

$d\sin \theta =n\lambda$

$\sin \theta =\frac{n\lambda }{d}=\frac{n\left(2000\right)}{\left(7000\right)}=\frac{n}{3.5}$

$\sin \theta \le 1$

$n=0,1,2,3,$ only

Total of only $7$ maximas obtained from the screen.