Question

Two identical coherent waves each of intensity $I_0$ are producing interference patterns. What is the value of resultant intensity at a point of destructive interference ?

• A. $4I_0$
  
• B. $I_0$
  
• C. $0$
• D. $2I_0$
  

Answer 1

The correct option is C $0$

The resultant intensity is given by,

$I_R=I_1+I_2+2\sqrt{I_1{I}_2}\cos \varphi$

Here, $I_1=I_2=I_0$

Ans at the point of destructive interference, $\varphi ={180}^0$

$\therefore I_R=I_1+I_2+2\sqrt{I_1{I}_2}\cos {180}^0$

$\Rightarrow I_R=2I_0-2I_0=0$

Hence, option $\left(C\right)$ is correct.