PPT-Light II

Physics 2415 Lecture 32 Michael Fowler UVa Todays Topics Huygens principle and refraction Snells law and applications Dispersion Total internal reflection Huygens Principle Newtons contemporary Christian Huygens believed light to be a wave and pictured its propagation as follows at any instant the wave front has reached a certain line or curve From every point on this wave front a . 11 detection ranges 147 to 1617 mm Light Curtains Light curtains are installed as safeguarding measures for personnel where A safety guard cannot be installed due to structural reasons A safety guard is openedclosed frequently Safety guards are not IP 64 NPN 12 bis 30V gepulst 10 kHz wwwwPulsating-light operation increases the insensitivity ofthe connected light barrier to outside light and dirtying(synchronous evaluation).The sensitivity can be 1. 2. What it light?. Part of the electromagnetic spectrum. 3. Electromagnetic spectrum. 4. Amplitude and wavelength. 5. Electromagnetic radiation types. R. abbits. M. ate. I. n. V. ery. U. nusual. e. Energy for all life on Earth ultimately comes from photosynthesis.. 6CO. 2. 12H. 2. O C. 6. H. 12. O. 6. 6H. 2. O 6O. 2. . Oxygenic photosynthesis is carried out by:. cyanobacteria. Bright light story. The farmer was crossing the field at dusk when a bright light was sighted in the sky. Upon reaching the farmhouse, Olson made a telephone call to the sheriff. The farmer grabbed a camera and dashed outdoors to get pictures. The next day the big news report in the local paper was an alleged UFO sighting.. Materials can be. . Transparent. - A material that transmits (allows through) light unaffected. . Translucent. - A material that transmits light but scatters it into different directions . . Opaque. Light. What is light?. . It is the electromagnetic . radiation that can be . perceived . by the human eye. It is made up . of.  . electromagnetic waves.  with wavelengths between . 4 . × 10. -7. Light. Light. Properties and Interactions. What is Light?. Light. is a form of energy emitted by the Sun..  . What is Light?. Light. is a type of energy that travels as an electromagnetic wave.. Lesson 2: How does light travel?. Lesson 3: Reflection. Lessons 4: Shadows. Lessons 5: Periscopes . More Lessons. Light Lessons. Lesson 6: Colours . Lesson 7: Refraction. Lesson 8: Invisible Light. Measurements of the speed of light:. c = 3 . × 10. 8. m/s = . 186,000 miles/s. light propagating through matter – . transparent vs. opaque. materials. colors. The bending of light – refraction. [Surah an . Nisa. -174]. STARTER: . Deduce the significance of the ayah.. O mankind! verily there hath come to you a convincing proof from your Lord: for We have sent unto you a light (that is) manifest. (Surah an Nisa174) . The elementary particle that defines light is the photon.. There are 3 basic dimensions of light. Intensity (amplitude) which is related to the perception of brightness. Frequency (wavelength), perceived as colour. Black is the absence of light.. This font is black because no light is shining here. . The light shines all around it making white. . Mixing colors. By mixing different colors you can create new colors.. When light encounters a different medium it can either be reflected, absorbed, or pass through. Most of the time it is some level of each.. A blue shirt reflects blue light (and a few others) absorbs all other colors of light and allows small intensities of all colors (white light) to pass through. .