Flashcards
OCR Gateway P1d
Cards in this deck (4)
- 1P1d - Lights and LasersMorse Code is a example of digital signal.
- 2Optical FibresAn optical fibre is a thin rod of high-quality glass. Very little light is absorbed by the glass. Light getting in at one end undergoes repeated total internal reflection, even when the fibre is bent, and emerges at the other end.
- 3LasersLasers produces an intense narrow beam of light. The light from a laser is monochromatic (a single colour).
The light waves have a low divergence (they spread out very little). They are coherent, which means that they are: the same frequency and in phase with each other.
When light waves are in the same phase, their crests all line up, as do their troughs. - 4Reading CD's and DVD'sLaser beams are used to read information from CDs in CD players. The shiny surface of a CD contains billions of microscopic pits in a spiral track. The pattern of pits contains digital information. The laser light is reflected off the surface of the CD as the disk spins, and is detected by:
- the change in the amount of reflected light caused by entering or leaving a pit is interpreted as a 1
- no change in the amount of reflected light is interpreted as a 0.
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- Flashcards on OCR Gateway P1d, created by Zaaaara on 19/05/2014.
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- Zaaaara
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