試題詳解

【已刪除】35. An air raid siren on top of a tall pole radiated sound waves uniformly in all directions. At a distance of 15.0 m, the intensity of the sound is 0.25 W/m². At how many meters from the siren is the intensity 0.01 W/m²?
(A)1.5
(B)30
(C)70
(D)150
(E)一律給分