Ch 1 light and sight
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1. Light can come from luminous objects that emit light or non-luminous objects that reflect light. Lasers emit a narrow beam of light from excited atoms acting together. 2. Light travels in straight lines called rays. A beam is a stream of many parallel rays of light. Beams can be parallel, converging, or diverging. 3. Shadows are formed when light is blocked by an opaque object. Small light sources make sharp shadows while large sources make shadows with a dark center and gray edges.
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Ch 1 light and sight
- 2. 1.Source of light Luminous object: object that give out light as the result of the excited atoms receive energy. Non luminous object: Object that not send out light. Laser: A type of light source in which their excited atoms act together and emit a narrow light.
- 3. 2.Rays and beams Rays travel in straight lines The path in which light pass= rays A beam is a stream of light. Beam of light can be parallel, converging, diverging.
- 4. 3.Shadows Opaque: Object that doesnt let light pass Small source of light give sharp shadows with dark color all over. Large large amount of light give a shadows with a pitch dark on the centre with gray area surrounds it. Umbra: Dark region Penumbra: Gray area
- 5. 4.Speed of Light Very fast Faster than sound
- 6. 5.Law of reflection Normal : an imaginary line that perpendicular 90 degree to the surface. Law of reflection : The angle of incidence equals angle of reflection.
- 7. 6.Periscope Instrument that use 2 mirrors.
- 8. 7.Regular and diffuse reflection Regular reflection is on a smooth surface. Diffuse reflection is on rough surface. Diffuse reflection does not follow law of reflection.
- 9. 8. Real image and Virtual image Real image is the image that can be from on screen and produced by light rays that passed through it. Virtual image is the image that cannot be produced on screen and produced by rays that seemed to pass through it but not.
- 10. 9. Lateral inversion This is an effect produced by plane mirror. Your left and right eyes are interchanged. Occurs whenever an image is formed by one reflection.
- 11. 10. Properties of plane mirror As far behind the mirror as the object is in front and the line joining the object and image is perpendicular to the mirror. The same size as the object. Virtual Laterally inverted
- 12. 11. Kaleidoscope A set of two mirror set at an angle to produce multiple image. Formula to find the image produce by two mirrors forming specific angle: 360 X - 1
- 13. 12. Facts about reflection Light ray that enter a denser medium have angle of reflection smaller than angle of incidence. A light ray is bent away from the normal when enter a less dense medium. A light ray is bent towards the normal if it enters a denser medium. A ray emerging from parallel sided block is parallel from ray that enter the block. A ray enter at the normal of an object is not refracted.
- 14. 13. Refraction index Refraction happens because change of speed of light. Reactive index = Speed of light in air or 1st medium Speed of light in 2nd medium
- 15. 14.dispersion The spread out of color spectrum when white color light pass through a prism.
- 16. 15.Critical angle The angle at which the angle of refraction is 90 degree. When the light does not pass the boundary it is said that it undergo total internal reflection.
- 17. 16.Multiple images It happened because of the multiple reflection inside a glass of mirror which cause blurring.
- 18. 17.Total reflecting prisms The prism which completely reflecting light rays.