After reading this page you will be bale to draw the image formation by lenses and understand how images are formed with convex lens and concave lens. but first of all there are certain rule that you should know in order to under stand the image formation.
Rules for image formation for convex lenses
1: All the light rays passing through the optical centre passes undeviated
2: Parallel rays after refraction meets at focus
3 : we project light ray on lens from focal point than it will become parallel to principal axis after refraction
when object placed beyond 2F1
when object placed at 2F1
when object placed between 2F1 and F1
when object placed at F1
when object placed between F1 and optical centre
when object placed at infinity
Rules for image formation for concave lenses
1: All the light rays passing through the optical centre passes undeviated
2: Parallel rays after refraction appears meets at focus
when object placed at any point except infinity
when object placed at infinity
