Q)
a)Draw a ray diagram for formation of images of a point object by a thin double convex lens having radii of curvatures $R_1$ and $R_2$ and hence derive lens makers formula.
b) Define power of a lens and give its S.I units . 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 ?
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