Light- Reflection and-refraction
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This document discusses key concepts about light, including its properties, reflection, and refraction. It defines light and its behavior as rays and beams. It explains the difference between luminous and non-luminous objects and how reflection allows us to see non-luminous objects. The document discusses the laws of reflection, including that the angle of incidence equals the angle of reflection. It also covers refraction, how the speed of light changes in different mediums based on density, and Snell's law governing the relationship between incident and refracted rays. It provides examples of how refraction affects how objects appear through different materials like water.
Light- Reflection and-refraction
- 2. Light is the part of the EM spectrum which we can see. Light travels in straight lines called rays. A bundle of rays is known as a beam of light. A ray A parallel beam A divergent beam A convergent beam
- 3. Luminous objects are those that give off light on its own. Example: Light bulb, Sun Non-luminous objects are objects that do not give off light on its own. Example: table, board, Moon
- 4. Reflection is the bouncing of light rays off a surface. We are able to see non-luminous objects as light is reflected off them.
- 5. Angle of incidence, i Angle of reflection, r normal Incident ray Reflected ray surface
- 6. The incident ray, the reflected ray and the normal all lie on the same plane. The angle of incidence is equal to the angle of reflection.
- 7. Regular reflection •On smooth surfaces Diffused reflection •On rough surfaces
- 8. Same size as the object Laterally inverted (left-to-right inversion) Upright Virtual (image cannot be caught on a screen) Object distance is equal to image distance
- 10. Ray Diagram for Reflection Image, I observer Object, O
- 11. observer
- 12. Refraction is the bending of light when it enters from one transparent medium into another. It is caused by the different speeds of light in different media. The greater the optical density of the medium, the slower the speed of light.
- 13. Incident ray Refracted ray Emergent ray Angle of incidence Angle of refraction normal Angle of emergence
- 14. The incident ray, the refracted ray and the normal all lie in the same plane. For two particular media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant. r i n sin sin = (Snell’s Law)
- 15. When light passes from vacuum (or air) into a given medium (eg. water), the constant ratio of is known as the refractive index, n, for that medium. r i sin sin r i n sin sin = Angle of incidence Angle of refraction
- 16. Speed of light in vacuum = 3 x 108 ms-1 Light is found to move slower in optically denser mediums. (eg. glass and water) v c =n mediuminlightofspeed in vacuumlightofspeed =n
- 17. Swimming pool and ponds appear shallower than it really is. Object is at a deeper depth than where it appears to be. Bent objects in liquids
- 18. Light ray is unable to exit a medium. Occurs when Ray of light passes from a denser to a less dense medium Angle of incidence in the denser medium is greater than the critical angle. http://www.lightlink.com/sergey/java/java/totintrefl/index.html
- 19. The angle of incidence in the optically denser medium for which the angle of refraction in the less dense medium is 90o . n c 1 sin = Refractiv e index Critical angle