Lenses only pptx

Lenses

1. LEARNING OBJECTIVES List types of lenses Describe the image formed by a lens. 3. Lenses Key concept : Systems, Related concepts : Development, consequences, Global Context :

2. Starter Read textbook page 12 to learn the different types of lenses https://www.liveworksheets.com/vz1372994lb

3. O: Center of lens (optical center) F: Focus, f : Focal length distance between F and O. C: Center of curvature, C = 2f Parts of lenses: Key concept : Systems, Related concepts : Development, consequences, Global Context : Fairness and development

4. Rules for ray diagrams in lenses: 1) Rays parallel to the principal axis will refract, passing through the focal point . 2) Rays passing through the center of the lens ‘O’ will continue in a straight line . 3) Rays passing through the focal point will refract parallel to the principal axis. Key concept : Systems, Related concepts : Development, consequences, Global Context : Fairness and development

5. Rules for ray diagrams in lenses: Use the simulation to practice drawing the image formed by a lens in different positions. https://www.physicsclassroom.com/Physics-Interactives/Refraction-and-Lenses/Optics-Bench/Optics-Bench-Refraction-Interactive

6. Conduct demo experiment 1.3 page 13 from textbook. Use link to show how light refracts in lenses. https://ophysics.com/l12.html https://www.physicsclassroom.com/Physics-Interactives/Refraction-and-Lenses/Optics-Bench/Optics-Bench-Refraction-Interactive

7. https://www.physicsclassroom.com/Concept-Checkers/Interactives/Optics-Bench-Lenses/Concept-Checker

8. Summary

9. Eyeglasses Cameras Optical micro scope Eye structure Some applications to lenses Magnifying glasses Key concept : Systems, Related concepts : Development, consequences, Global Context : Fairness and development

10. Some applications to lenses Watch the video https://www.youtube.com/watch?v=HAW_6ukFO9w to answer the questions in the next slides State the name of the two main types of telescopes. Reflecting telescopes. Refracting telescopes. Key concept : Systems, Related concepts : Development, consequences, Global Context : Fairness and development

11. Applications of lenses Refracting telescope Reflecting telescope use lenses. use mirrors require a much purer material Does not require a much purer material can not be made very large can be made much larger suffer more from aberrations suffer less from aberrations used more for photography. used more for astronomy Key concept : Systems, Related concepts : Development, consequences, Global Context : Fairness and development

12. Applications of lenses The astronomical observatories are generally situated on mountaintops. Explain the reason behind this. You need to post your answer on Padlet Key concept : Systems, Related concepts : Development, consequences, Global Context : Fairness and development

13. Vision problems and refraction Textbook pages 24-25 Read page 16 in your textbook “structure of human eye” to identify the different parts of human eye and their functions (WS on MB) Key concept : Systems, Related concepts : Development, consequences, Global Context : Fairness and development

14. An image is formed on the retina with light rays converging most at the cornea and upon entering and exiting the lens . Rays from the top and bottom of the object are traced and produce an inverted real image on the retin a. How eyes work Textbook pages 24-25 Key concept : Systems, Related concepts : Development, consequences, Global Context : Fairness and development

15. (a) The nearsighted ( Short-sightedness ) ( myopic ) eye converges rays from a distant object in front of the retina ; thus, they are diverging when they strike the retina, producing a blurry image . This can be caused by the lens of the eye being too powerful or the length of the eye being too great. Require concave lens. Vision problems and refraction Textbook pages 24-25 Key concept : Systems, Related concepts : Development, consequences, Global Context : Fairness and development

16. (b) The farsighted ( Long-sightedness ) ( hyperopic ) eye is unable to converge the rays from a close object by the time they strike the retina, producing blurry close vision . This can be caused by insufficient power in the lens or by the eye being too short. Require convex lens. Vision problems and refraction Textbook pages 24-25 Key concept : Systems, Related concepts : Development, consequences, Global Context : Fairness and development

17. Check your understanding: Worksheet on vision problems (MB or hardcopy) Key concept : Systems, Related concepts : Development, consequences, Global Context : Fairness and development https://ophysics.com/l16.html