Question

A is singing a note and at the same time B is singing a note with exactly one-eighth the frequency of the note of A. The energies of two sounds are equal, the amplitude of the note of B is

• A. Same that of A
• B. Twice as that of A
• C. Four times as that of A
• D. Eight times as that of A

Answer 1

Answer: (D)

Eight times as that of A

Answer 2

Energy $\propto a^{2}n^{2}$⇒ $\frac{a_{B}}{a_{A}} = \frac{n_{A}}{n_{B}}$

($\because$energy is same)

⇒ $\frac{a_{B}}{a_{A}} = \frac{8}{1}$