Two light sources can be adjusted to emit monochromatic light of
any visible wavelength. The two sources are coherent, 3.53 µm
apart, and in line with an observer, so that one source is 3.53 µm
farther from the observer than the other.

(a) For what visible wavelengths (400 to 700 nm) will the
observer see the brightest light, owing to constructive
interference? (Enter your answers from smallest to largest starting
with the first answer blank. Enter NONE in any remaining answer
blanks.)

(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 3.53 µm farther away from the observer than
the other?

(c) For what visible wavelengths will there be
destructive interference at the location of the observer?
(Enter your answers from smallest to largest starting with the
first answer blank. Enter NONE in any remaining answer blanks.)