If you have access to an overhead projector, examine the device carefully so that you can describe the optical system involved.
a. What optical elements (lenses or mirrors) are present?
b. What is the function of each of these elements? (Holding a white card or stiff paper at various places between the elements when the projector is in use may help you analyze their function.)
c. Can you produce a ray diagram showing how the rays coming from the object (the transparency being viewed) converge or diverge on their way to the screen?