Answer:
(C) The intensity will drop to 250 W/m² when the frequency is changed to 2.0 MHz at this particular depth.
Step-by-step explanation:
Sound intensity is directly proportional to its frequency.
F ∝ I
Sound intensity is inversely proportional to square of distance
I ∝1/r²,
Therefore, F ∝ 1/r²
From the question we were given the following;
F₁ initial frequency = 1.0MHz
I₁ initial intensity = 1000 W/m₂
F₂ Final frequency = 2.0 MHz
When the frequency was set to 1 MHz, the intensity dropped to 500 W/m² at this certain depth.
Hence the decreasing factor = 1000/500 = 2
When the frequency is set to 2 MHz, the depth will drop by 2²
The new intensity = 1000/4 = 250 W/m²
Therefore, the intensity will drop to 250 W/m² when the frequency is changed to 2.0 MHz at this particular depth.