I am a high school student learning Physics. I am currently learning about diffraction of waves, be it water waves, light waves each, in systems where there are 2 slits for it to diffract through.
I have 2 questions about this diffraction:
Where are the peaks and where are the troughs of the waves in the diagrams? Are the blank spaces the troughs and the red lines the peaks?
I understand that constructive interference occurs when the peaks of 2 waves align, and destructive interference when the peak of the wave hits the trough of another wave. But why in the diagram above does constructive interference occur in the center (represented by bright)? And why does destructive interference occur on the 2 sides of the center (represented by dark), followed by another 2 zones of constructive interference (represented by bright)?
Can all this be explained at the level of a high school student, and without Calculus based mechanics?