1. The eye: parts, formation of image, kind, how, where.
2. Eye defects, how remedied. Visual angle.
3. Simple microscope, camera; images, kind, how formed.
4. Compound microscope, telescope and opera glass; images, action of each lens.
Exercises
1. Name three instruments in which lenses form virtual images and three in which real images are formed.
2. In what direction is an oar in water apparently bent? Explain by a diagram.
3. What optical instruments have you used? Is the visible image formed by each of these real or virtual?
4. The focal length of a copying camera lens is 14 in. Where must a drawing be placed so that an image of the same size may be formed upon the ground glass screen? What must be the distance of the screen from the lens?
5. What are two methods by which you can determine the focal lengths of the lens of a photographic camera?