(C) Principal axis, images formed when object is in various locations.
(D) Computation of location of images.
Exercises
1. Why is an image of a candle formed by an aperture, not sharply defined?
2. When a photographer takes your picture and moves the camera nearer you, must he move the ground glass screen toward the lens or away from it? Explain.
3. How can you find the principal focal length of a lens.
4. How can you test a spectacle lens to see whether it is convex concave?
5. When will a convex lens produce a virtual image? Have you ever seen one? Where?
6. When a photographer wishes to obtain a full length view of a person, where does he place the camera?
7. The focal length of the lens is 24 cm. How far from the lens must an object be placed in order that a real image may be three times as long as the object?