Monochromatic light of wavelength 491 nm illuminates two parallel narrow slits 6.93 μm apart. Calculate the angular deviation of the third-order (for m = 3) bright fringe (a) in radians and (b) in degrees.

To solve this problem we will apply the concepts related to the double slit experiment. Here we test a relationship between the sine of the deviation angle and the distance between slit versus wavelength and the bright fringe order. Mathematically it can be described as,

Here,

d = Distance between slits

m = Any integer which represent the order number or the number of repetition of the spectrum

= Wavelength

= Angular deviation

Replacing with our values we have,

Part A)

PART B)

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