An elongated beam of red light from a He-Ne laser (λ0 = 632.8 nm) is incident on a screen containing two very narrow horizontal slits separated by 0.2 mm. A fringe distribution appears on a white screen placed at a distance of 100 m. (a) How far (in radians and millimeters) above and below the central axis are the first zeros of irradiance? (b) How far (in mm) from the axis find the fifth bright fringe? (c) Compare these two results.

An elongated beam of red light from a He-Ne laser (λ0 = 632.8 nm) is incident on a screen containing two very narrow horizontal slits separated by 0.2 mm. A fringe distribution appears on a white screen placed at a distance of 100 m. (a) How far (in radians and millimeters) above and below the central axis are the first zeros of irradiance? (b) How far (in mm) from the axis find the fifth bright fringe? (c) Compare these two results.