Question

For the given two identical wave pulses, the resultant wave pulse when they interfere at a point at the same line of motion is -

• A.
• B.
• C.
• D.
  

Answer 1

The correct option is B


The given two identical wave pulses are out of phase by ${180}^{\circ }$, so phase difference, $\varphi ={180}^{\circ }$.

Now, the resultant amplitude,

$A_{\text{net}}=\sqrt{A_1^2+A_2^2+2A_1{A}_2\cos \varphi }$

$\Rightarrow A_{\text{net}}=\sqrt{A_1^2+A_2^2+2A_1{A}_2\cos {180}^{\circ }}$

$\Rightarrow A_{\text{net}}=|A_1-A_2|=A_2-A_1=5-2=3\text{cm}$

Hence, option $\left(B\right)$ is the correct answer.