1. Chapter 25 Optical Instruments 1. The eye 2. The magnifying glass

2. The Eye - Parts Cornea Aqueous Humor – The pupil The crystalline lens The iris

3. The Eye – Operation The cornea-lens system Rods and Cones Accommodation

4. The Eye – Focusing The eye can focus on a distant object The eye can focus on near objects The near point The far point

5. Farsightedness

6. Nearsightedness

7. Presbyopia, Astigmatism and Diopters Presbyopia Astigmatism Diopters

8. Example What focal length must a corrective lens have to enable the eye to see clearly an object 25.0 cm away if the near point is 50 cm away? What is the power of this lens?

9. Example A particular nearsighted person cannot see objects clearly when they are beyond 25 cm (the far point of the eye). What focal length should the prescribed lens have to correct this problem? What is the power of this lens?

10. Simple Magnifier What is it? How does it work? What is angular magnification? How do I calculate it? What is the near point of the eye? Single and Multiple lens

11. Example - Simple Magnifier 1. A magnifying glass has a focal length of 15cm. If the near point of the eye is 25 cm from the eye, what is the angular magnification of the glass.

12. Compound Microscope A compound microscope consists of two lenses Gives greater magnification than a single lens The objective lens has a short focal length, ƒ o <1 cm The ocular lens (eyepiece) has a focal length, ƒ e, of a few cm

13. The Camera The single-lens photographic camera is an optical instrument Components Light-tight box Converging lens Produces a real image Film behind the lens Receives the image