(i) Draw a ray diagram for formation of image of a point object by a thin double convex lens having radii of curvatures `R_1 and R_2` and hence, derive lens maker's formula. (ii) Define power of a lens and give its SI unit. If a convex lens of length 50 cm is placed in contact coaxially with a concave lens of focal length 20 cm, what is the power of the

Question

(i) Draw a ray diagram for formation of image of a point object by a thin double convex lens having radii of curvatures `R_1 and R_2` and hence, derive lens maker's formula.
(ii) Define power of a lens and give its SI unit. If a convex lens of length 50 cm is placed in contact coaxially with a concave lens of focal length 20 cm, what is the power of the combination?