Glass surface — UPSC Physics Optional CSE 2006 Paper I

Obtain the relation to find radii of the rings and the wavelength of light in Newton's circular ring. Calculate the radius of curvature of the convex glass surface where diameter of 5^{th} and 15^{th} bright rings formed by sodium yellow light are measured to be 2.303\text{ mm} and 4.134\text{ mm}. Given \mu = 1.5 and \lambda_{yellow} = 5282 \text{\AA}.