Question

The superposition takes place between two waves of frequency $f$ and amplitude $a$ . The maximum intensity $I_{max}=constant\times$ ____

• A. $a$
• B. $2a$
• C. $2a^2$
• D. $4a^2$

Answer 1

Answer: (D)

Resultant amplitude
$A=\sqrt{a^2+a^2+2aacos\varphi }=\sqrt{4a^2{\left(cos\right)}^2\left(\frac{\varphi }{2}\right)}$
$A=2acos\left(\frac{\varphi }{2}\right)$
$\therefore I\propto A^2$
$\Rightarrow I\propto 4a^2$