A plano-convex glass lens of radius of curvature 1.4 m rests on an optically flat glass plate. The arrangement is illuminated from above with monochromatic light of 520-nm wavelength. The indexes of refraction of the lens and plate are 1.6. Determine the radii of the first and second bright fringes in the reflected light.

Given that,

Radius of curvature = 1.4 m

Wavelength = 520 nm

Refraction indexes = 1.6

We know tha,

The condition for constructive interference as,

Where,

We need to calculate the radius of first bright fringes

Using formula of radius

Put the value of t

Put the value into the formula

We need to calculate the radius of second bright fringes

Using formula of radius

Put the value into the formula

Hence, The radius of first bright fringe is 0.603 mm

The radius of second bright fringe is 1.04 mm.

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