(a) Explain why, a real image can be projected on a screen but a virtual image cannot.(b) Draw a ray diagram to show the formation of a real diminished image of an object by a convex lens. In your diagram, the position of object and image with respect to the principal focus should be shown clearly.(c) Name one simple optical instrument in which the above arrangement of convex lens is used.

(a) A real image can be projected on a screen unlike a virtual image because a real image is formed when light rays coming from an object actually meet at a point after refraction through a lens. While a virtual image is formed when light rays coming from an object only appear to meet at a point when produced backward (but do not actually meet) after refraction through a lens.

(b) When an object is placed beyond $2F'$, the image formed by the convex lens is real, inverted, and diminished.

The diagram given below, showing the position of object and image with respect to the principal focus.

(c) A camera is a simple optical instrument in which the above arrangement of the convex lens is used because the camera lens produces a small, real, and inverted image of an object on the film.