Question

A sound wave strikes a student’s eardrum with a power of 22 μW. The sound’s intensity at the eardrum is 0.95 W/m2.

Assuming a circular eardrum, what is the radius of the student’s eardrum, in millimeters?

The same sound wave delivers the same power to the eardrum of a second student. His eardrum has a 14 % larger radius than that of the first student. What is the intensity of the sound, in watts per square meter, at the second student’s eardrum?

Answer 1

Intensity (I) of a wave is the power radiated through unit area, i.e.,

where,

P = power of the sound wave =

Assuming the eardrum to be circular of radius R, its area,

I = Sound intensity at the eardrum =  0.95 W/m²

The radius of the eardrum of the second student is and is 14% larger than the first student.

Area of the eardrum of the second student,

Intensity of sound at the second eardrum,

Regards