Question

The intensity ratio of two waves is $1:9$. The ratio of their amplitudes, is

• (A) $3:1$
• (B) $1:3$
• (C) $1:9$
• (D) $9:1$

Answer 1

The Correct Option is B

Explanation:
Intensity $\propto$ (amplitude) ${}^2$ $\therefore \frac{I_1}{I_2}=\frac{a_1^2}{a_2^2}$$\Rightarrow \frac{1}{9}=\frac{a_1^2}{a_2^2}$$\Rightarrow \frac{a_1}{a_2}=\frac{1}{3}$$\Rightarrow a_1:a_2=1:3$Hence, the correct option is (B).