(i) A point object is placed in front of a double convex lens (or refractive index `mu=n_2/n_1` with respect to air) with its spherical faces of radii of curvature `R_1 and R_2` Show the path of rays due to refraction at first and subsequently at the second surface to obtain the formation of the real image of the object. Hence, obtain the lens maker's formula for a thin lens. (ii) A double convex lens having both faces of the same radius of curvature has refractive index 1.55. Find out the radius of curvature of the lens required to get the

Question

(i) A point object is placed in front of a double convex lens (or refractive index `mu=n_2/n_1` with respect to air) with its spherical faces of radii of curvature `R_1 and R_2` Show the path of rays due to refraction at first and subsequently at the second surface to obtain the formation of the real image of the object. Hence, obtain the lens maker's formula for a thin lens.
(ii) A double convex lens having both faces of the same radius of curvature has refractive index 1.55. Find out the radius of curvature of the lens required to get the focal length of 20 cm.