1. The problem statement, all variables and given/known data Three speakers with the same effect are connected to the same tone generator are placed along the y-axis and sends out sound in equal directions. The distance a and b are in the same magnitude as the wave length of the sound. http://s716.photobucket.com/user/Pitoraq/media/Fys21_zps1596efc1.png.html a) The point P is located on a distance L >> a from the speakers along the x-axis. If only one speaker is connected the intensity in the point P is 15.0 mW/m^2. Which is the total intensity when all speakers are connected ? b) If the distance a = λ/4, which is the smallest distance b that gives maximum intensity along the y-axis from a distance L ? 2. Relevant equations I = P/A P(0) = (2vρI)^(1/2) I = P(0)/(2vρr^2) 3. The attempt at a solution I = P/A ρ = 1.2929 kg/m^2 density of air P(0) = (2vρI)^(1/2) = 115.5 pa I = P(0)/(2vρr^2) <==> r = P(0)/(2vρI)^(1/2) = 31.62 m If r is the distance from the point P to one of the three speakers, i dont know which one. And what do they mean with "The distance a and b are in the same magnitude as the wave length of the sound." ?