Two slits separated by a distance of d = 0.185 mm are located at a distance of D = 2.06 m from a screen. The screen is oriented parallel to the plane of the slits. The slits are illuminated by a monochromatic and coherent light source with a wavelength of ? = 632 nm. A wave from each slit propagates to the screen. The interference pattern shows a peak at the center of the screen (m=0) and then alternating minima and maxima.
What is the path length difference between the waves at the first maximum (m=1) on the screen?
At what angle from the beam axis will the first (m=1) maximum appear? (You can safely use the small angle approximation.)