Answer:
Emitted power will be equal to [tex]7.85\times 10^{-5}watt[/tex]
Explanation:
It is given factory whistle can be heard up to a distance of R=2.5 km = 2500 m
Threshold of human hearing [tex]I=10^{-12}W/m^2[/tex]
We have to find the emitted power
Emitted power is equal to [tex]P=I\times A[/tex]
[tex]P=I\times 4\pi R^2[/tex]
[tex]P=10^{-12}\times 4\times 3.14\times 2500^2=7.85\times 10^{-5}watt[/tex]
So emitted power will be equal to [tex]7.85\times 10^{-5}watt[/tex]
