The radius of curvature of the convex surface of a planoconvex lens is 95.2 cm. The lens

Question:

The radius of curvature of the convex surface of a planoconvex lens is 95.2 cm. The lens is placed convex side down on a perfectly flat glass plate lhat is illuminated from above with red light having a wavelength of 580nm. Find the diameter of the second bright ring in the interference pattern.