In a Young’s double-slit experiment, a set of parallel slits with a separation
Of 0.100 mm is illuminated by light having a wavelength of 589 nm and the interference
Pattern observed on a screen 4.00 m from the slits. (a) What is the difference in path
Lengths from each of the slits to the screen location of a third-order bright fringe? (b)
What is the difference in path lengths from the two slits to the screen location of the third
Dark fringe away from the center of the pattern?

What causes dark and bright fringes?

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