Question

(a)

Calculate the minimum safe distance (in m) you can be from a speaker that puts out 1.20 W of sound, using the following assumptions. The sound power spreads uniformly over a sphere of radius r and area 4?r², your eardrum area is 0.720 cm², and it cannot tolerate more than 1.00 ? 10^?6 W. Damage is done by this small amount of power after prolonged exposure and can be repaired by the body, but damage done by 10^?4 W (found at many rock concerts) occurs almost instantaneously and prolonged exposure at that level produces permanent damage.

m

(b)

1.20 W of sound power is very large compared to what the ear can tolerate. Suppose that 100 W of electrical power input (a typical value for many sound systems) is applied to this speaker. What is the efficiency of this speaker in converting electrical power to sound?

%

Answer 1