1. The problem statement, all variables and given/known data Two loudspeakers connected to the same source produce sound waves in plase with the same amplitude. The frequency of the sound is 215 Hz and the speed of the sound is 344 m/s. A girl finds that when she stands at a point that is 15.0m from one source and 19.0m from the other she hears no sound. Find: a) the number of the nodal line on which the girl is located. b) the minimum increase in frequency which would enable the girl to hear a maximum sound at the same location 2. Relevant equations l S1-S2 l = (n- 1/2) wavelength v= f(wavelength) 3. The attempt at a solution a) f= 215 Hz v= 344 m/s S1= 15.0m S2= 19.0m wavelength? n=? v= f(wavelength) wavelength= 344/ 215 wavelength= 1.6m l S1- S2 l= (n-1/2)(wavelength) n= (lS1-S2l)/(wavelength) +0.5 n= (l 15.0-19.0l)/1.6m + 0.5 n=3 b) I don't really understand this part of the question, or how to find it so any help would be very much appreciated. Thanks!