Therefore, both the refracted rays are produced backwards so that they meet at a point to form an image. Thus, both the light rays diverge after refraction through the lens and does not meet. Another ray of light from the object passes through the optical centre of the lens and thus as per the rule goes straight after refraction through the lens. Therefore, as per the rule, it passes through another focus after refraction through the lens. The type of image formed by a convex lens depends on the position of the image.Ĭase 1: If the object is placed between optical centre and focus ( between C and F’ ) then the first ray of light starting from the top of the object is parallel to the principal axis. Rule 3: When a ray of light passes through the focus of the convex lens then it becomes parallel to the principal axis after refraction through the lens. Also, a ray of light going along the path of principal axis of a convex lens also goes straight and does not deviate. Rule 2: A ray of light passing through the optical centre of the convex lens does not bent after refraction but goes straight. Rule 1: A ray of light which is originally parallel to the principal axis passes through the focus after refraction through the lens.
In convex lens, the image is always formed at a point where at least two refracted light rays meet. Rules for obtaining images formed by convex lens The distance between optical centre and principal focus is called focal length of a concave lens. The image formed by this lens is virtual. If the parallel light rays fall from the left side than they appear to diverge from a point of the left side only and if the light rays fall from the right hand side that they appear to diverge from a point on right hand side.Ī concave lens is also known as diverging lens. The parallel beam of light rays is diverged after passing through it. Thus refracted rays appear to diverge from the focus.