Image Formation by Lens:
For making the image by thin lens, the ray diagram is traced according to following three rules.
(i) The rays passing through optical centre emerge from the lens without deviation.
(ii) The ray coming parallel to the principal axis, after refraction from the lens, meet at focus in convex lens and or appear to diverge from the focus in concave lens, (figure)
(iii) The rays passing through the focus of convex lens or coming toward the focus of concave lens, become parallel to the principal axis after refraction through the lens (figure)
