wave_mechanics musical_sound Question 15

Question: The intensity of sound wave while passing through an elastic medium falls down by 10% as it covers one metre distance through the medium. If the initial intensity of the sound wave was 100 decibels, its value after it has passed through 3 metre thickness of the medium will be

[CPMT 1988]

Options:

A) 70 decibel

B) 72.9 decibel

C) 81 decibel

D) 60 decibel

Show Answer

Answer:

Correct Answer: B

Solution:

After passing the 3 meter intensity is given by $ I _{3}=\frac{90}{100}\times \frac{90}{100}\times \frac{90}{100}\times I=72.9%\ \text{of }I $ So, the intensity is 72.9 decibel.