In: Physics
Students are sitting in a classroom and listening to a lecture. If the lecture has a sound level of 65 dB to the student sitting in the front row, what is the sound level according to another student sitting 3 times further away?
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Sound level of the lecture for the student sitting in the front row = 1 = 65 dB
Sound intensity of the lecture for the student sitting in the front row = I1
Distance of the student in the front row from the sound source = R1
I1 = 3.162 x 10-6 W/m2
Distance of another student from the sound source = R2
The other student is sitting 3 times further away.
R2 = 3R1
Sound intensity of the lecture for the other student = I2
The power of the sound is distributed equally in all directions that is in a spherical manner therefore,
I2 = 3.513 x 10-7 W/m2
Sound level of the lecture for the other student = 2
2 = 55.45 dB
Sound level according to another student sitting 3 times further away = 55.45 dB