3. Ratio of intensities of two waves are given by 4 : 1. Then the ratio of the amplitudes of the two waves is ?

3. Ratio of intensities of two waves are given by 4 : 1. Then the ratio of the amplitudes of the two waves is ?

(a) 2 : 1

(b) 1 : 2

(c) 4 : 1

(d) 1 : 4

Answer :  (a) 2 : 1

\( \frac{I_1}{I_2} = \frac{4}{1} \)

\( I \propto A^2 \)

\( \frac{I_1}{I_2} = \frac{A_1^2}{A_2^2} = \frac{4}{1} \)

\( \frac{A_1}{A_2} = \frac{2}{1} \)