Q. 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
A) $70\ decibel$
B) $72.9\ decibel$
C) $81\ decibel$
D) $60\ decibel$
Explanation
(b) After passing the 3 meter intensity is given by
$I_{3} = \frac{90}{100} \times \frac{90}{100} \times \frac{90}{100} \times I = 72.9\%\ of\ I$
So, the intensity is 72.9 decibel
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.