Question

Two waves of frequencies $1Hz$ and $3Hz$ are moving in a medium with same velocity. The ratio of intensities at a point where amplitudes of two waves are equal will be

• A. $1:1$
• B. $1:4$
• C. $1:2$
• D. $1:9$

Answer 1

Answer: (D)

$1:9$

Average intensity $I_{average}=2{\pi }^{2}m{A}^2{\nu }^{2}v$.
So $\frac{I_1}{I_2}=\frac{{\nu }_1^2}{{\nu }_2^2}=\frac{1}{9}$.