Question

In Young's double slit experiment using two identical slits, the intensity of the maximum at the centre of the screen is I. What will be the intensity at the centre of the screen if one of the slits is closed?

• A. I
  
• B. $\frac{I}{2}$
  
• C. $\frac{I}{4}$
  
• D. None of these

Answer 1

The correct option is C

$\frac{I}{4}$

Let $I_0$ be the intensity at the centre of the screen due to each slit. Then, for the central maximum, the intensity is
$I=I_0+I_0+2\sqrt{I_0{I}_0}=4I_{0}or{I}_0=\frac{I}{4}.$