A parallel ray converges at focus of a convex lens and diverges from the focus of a concave lens.
A ray passing through principal focus emerges parallel to the principal axis after refraction from a convex lens.
A ray passing through the principal focus emerges parallel to the principal axis after diverging from a concave lens.
Ray passing through the optical centre of convex and concave lens emerges in same direction without any deviation.
A convex lens is known as converging lens because parallel rays converge at its focus.
A concave lens is known as diverging lens because parallel rays diverge from its focus.
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