The spherical surface of a piano-convex lens comes into contact with a glass plate. The space between the lens and the plate is filled up with carbon dioxide. The refractive indices of the lens, carbon dioxide, and the plate are equal to n1 = 1.50, n2 = 1.63, and na = 1.70 respectively. The curvature radius of the spherical surface of the lens is equal to R =- 100 cm. Determine the radius of the fifth dark Newton's ring in reflected light with wavelength λ = 0.50