Fig Photograph of interference fringes produced on a screen in Young’s double slit experiment.

Fig Two radio antennas broadcasting in phase. Red arrows indicate directions of maximum intensity.

Fig Phasor diagram for the superposition (addition) at a point of two waves of equal amplitude E with a phase difference of . The resultant wave has amplitude of E p.

Fig Intensity distribution in the interference pattern from two identical slits. The maxima occur at points where  is an integral multiple of 2  and the path difference d = sin  is an integral multiple of.

Fig Interference between rays reflected from the upper and lower surfaces of a thin film. Constructive and destructive interference occur at different points along the film.

Fig Interference between two light waves reflected from the two sides of an air wedge separating two glass plates. The path difference is 2 t.