1. PHY 1371Dr. Jie Zou1 Chapter 36 Image Formation (Cont.)

2. PHY 1371Dr. Jie Zou2 Outline Thin lenses Thin lens equation Lens makers’ equation Ray diagrams for thin lenses Magnification of thin lenses

3. PHY 1371Dr. Jie Zou3 Lenses How does a lens work: Light passing through a lens experiences refraction at two surfaces. The image formed by one refracting surface serves as the object for the second surface.

4. PHY 1371Dr. Jie Zou4 Thin lens equation Thin lens equation: f: the focal length of a thin lens, also the image distance corresponding to p = . Each lens has two focal points, F 1 and F 2. Lens makers’ equation: Follow the sign conventions for thin lenses. Magnification: M = h’/h = -q/p Biconvex (converging) lens Biconcave (diverging) lens

5. PHY 1371Dr. Jie Zou5 Sign conventions for thin lenses

6. PHY 1371Dr. Jie Zou6 Ray diagrams for thin lenses

7. PHY 1371Dr. Jie Zou7 Examples 1. A diverging lens has a focal length of -20.0 cm. An object 2.00 cm tall is placed 30.0 cm in front of the lens. Locate the image. 2. A converging lens of focal length 10.0 cm forms an image of each of three objects placed (a) 30.0 cm, (b) 10.0 cm, and (c) 5.00 cm in front of the lens. In each case, find the image distance and describe the image.

8. PHY 1371Dr. Jie Zou8 Homework Ch. 36, P.1170, Problems: #28, 30, 40.