To construct a ray diagram, we use two light rays which are so chosen that it is easy to know their directions after reflection from the lens. List these two rays and state the path of these rays after refraction. Use these two rays to locate the image of an object placed between 'F' and '2F' of a convex lens.

The following are the rays of light used to find image after reflection-

1. The ray striking the optical center of mirror. Since the normal to the mirror at this point is the optical axis of the mirror itself, the angle the incident light forms with the horizontal is equal to the angle of reflected light with the same.
2. A parallel ray of light(with respect to optical axis of mirror) passing through the object strikes the mirror and reflects to pass through its focus.