Question

In $YDSE$ interference pattern produced by two identical slits, the intensity at the site of the central maximum is $I$. the intensity at the same spot when either of two slits is closed is

• A. $0.5I$
• B. $0.25I$
• C. $2I$
• D. $I$

Answer 1

The correct option is B $0.25I$

Let the amplitude of waves is A

Therefore,

$A_{max}=A+A=2A$

Now,

$I_{max}={A_{max}}^2={\left(2A\right)}^2=4A$

Let intensity of each split is $I_0$

Then,

When one split is closed

$I_0=\frac{I_{max}}{4}=0.25I$

correct option is B.