2. Converging lenses

3. Diverging Lenses

4. The Lens Equation We can make use of the fact that changing the focal length and position of the object we can change the size of the image created. The lens maker equation relates the distance of the object and image with the focal length

5. Using the “thin lens” equation: A few rules are necessary to use the equation: Object distances are always positive Image distances are positive for real images (when the image is on the opposite side of the lens as the object) and negative for virtual images (when the image is on the same side of the lens as the object). The focal length is positive for converging lenses and negative for diverging lenses.

6. Thin Lens Examples A converging lens has a focal length of 20 cm. An object is located 50 cm from the lens. What type of image will be formed, and where will it be located?

7. Magnification Many applications of lenses involve magnification. Magnification helps us see distant or small objects. For Example: a toy is placed 8 cm in front of a lens. An upright, virtual image of magnification 3 is seen. Where is the image located?

8. Applications of Optics What common devices use lens or mirrors? Overhead projector Telescope Microscope Binoculars Cameras Eye glasses Human eye

9. Telescopes Telescopes can be primarily composed of refracting lenses or reflecting mirrors.

10. Simplistic Telescope Diagrams

11. Telescope Optics

12. Magnifying Glasses What type of lens do you expect magnifying lenses use?

14. Overhead Projectors:

15. Eyes Eyes are complex optical devices! Notice the blind spot? What would happen if the focal point changed?

16. Corrective Lenses Eye glasses are used to ensure the image is focused on the sensors at the back of the eye.

17. Binoculars

18. Gravitational Lensing Lenses can take other forms…. Including galaxies or other massive objects. Objects with very high gravity bend light like a lens. This can create optical illusions!