A ray of light is incident on a lens parallel to its principal axis. After refraction, the ray passes through or appear to come from :
its first focus
its optical centre
its second focus
the centre of curvature of its second surface
The correct option is C its second focus The parallel rays of light meet at a point on the principal axis after refraction by a convex lens or appear to come from a point on the principal axis after refraction by a concave lens. This point is known as the second focus of the lens.