I'm confused as to how they determined which wave corresponded to which harmonic. I assumed the wave with the largest wavelength (solid line) was the 3rd harmonic, because from looking at graphs 1B and 1C, it looks like the peak amplitudes (both positive and negative amplitude peaks) got larger. The solid line looks like it has the largest amplitude out of the three, so I assumed the addition of the solid one formed the composite wave seen in 1C, thus the solid one was the 3rd harmonic....
Physics Q Pack #7
Physics Q Pack #7