Double Slit Interference 3

Double slit diffraction showing wavelengths along the two paths.
What happens to the diffraction pattern as you change the distance between the slits? [br][br]What happens to the diffraction pattern as you change the width of the slits?[br][br]Why are the two angles marked theta the same?[br][br]Why is the path length difference d*sin(theta)?

Information: Double Slit Interference 3