A sound wave traveling in 20ºC air has a pressure amplitude of 0.5 Pa. What is the intensity of the wave?
Intensity is defined as power over an area. It's given by
The intensity of a sound wave is given by the following eq'n:
Given this equation, along with constants, you can substitute your values and solve.
The constant for the speed of sound in air at 20*C is 343
The density of air is 1.2041
I use my Physics for Scientists and Engineers (9th ed.) and my professor's notes to find equations and constants for most problems, including this one. Good luck!