Two light sources can be adjusted to amit monochromatic light of any visible wavelength. The two sources are coherent, $2\mathrm{.}04$ um apart, and in line with an observer, so that one source is $2\mathrm{.}04$um farther from the observer than the other. $($a$)$ For what visible wavelengths $(380$ to $750$ nm$)$ will the observer see the brightest light, owing to constructive interference? $($b$)$ How would your answers to part a be affected if the two sources were not in line with the observer, but were still arranged so that one source is $2\mathrm{.}04$ um farther away from the observer than the other? $($c$)$ For what visible wavelengths wil lthere be destructive interference a the location of the observer?