In young’s double slit experiment, the measured fringe width is 0.5 mm for a sodium light of 589 nm at a distance of 1.5 m. a bright fringe is at a distance of 1 cm from the center.
a) find the order of the bright fringe
b) calculate the width of the bright fringe

(A).  The order of the bright fringe is 6.

(B). The width of the bright fringe is 3.33 μm.

Explanation:

Given that,

Fringe width d = 0.5 mm

Wavelength = 589 nm

Distance of screen and slit D = 1.5 m

Distance of bright fringe y = 1 cm

(A) We need to calculate the order of the bright fringe

Using formula of wavelength

Put the value into the formula

(B). We need to calculate the width of the bright fringe

Using formula of width of fringe

Put the value in to the formula

Hence, (A).  The order of the bright fringe is 6.

(B). The width of the bright fringe is 3.33 μm.