Light and lasers - P1d

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  • Created by: iram_f
  • Created on: 24-09-14 17:58
What happens at the critical angle?
If the angle of incidence is equal to the critical angle then light travels along the glass-air boundary.
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What are optical fibres?
Optical fibres are long, flexible, transparent cables that can send large amounts of information in the form of pulses of light or infrared radiation. These light pulses are totally internally reflected along their length, due to its boundary.
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How do we read CDs using lasers?
The reflective surface of a CD contains billions of minuscule pits (bumps), which store digital information. When the CD spins, laser light is reflected by the pits and these reflected pulses of light are turned into electrical signals.
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What is wireless technology?
Wireless technology is the use of electromagnetic radiation, like microwaves, to send information without optical fibres as it can be reflected and refracted. Its signals are available 24/7, no wiring is needed and items can be portable & convenient.
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What happens at total internal reflection?
Total internal reflection (TIR) occurs when the angle of incidence is above the critical angle, so light is TIR instead of refracted.
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What are lasers and some of their uses?
Lasers produce an intense, narrow beam of light that is monochromatic (containing only one colour from the spectrum), coherent, so they are in phase with each other and have the same frequency. They are used in surgery, weapon guidance and cutting.
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What are some advantages of using radiowaves as opposed to light to send signals?
Radiowaves diffract well as they have the longest wavelength, but light can't diffract well so it's not used for wireless signalling. However light travels very fast & there is a small loss of signal, yet diffraction of radiowaves causes signal loss.
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Other cards in this set

Card 2

Front

What are optical fibres?

Back

Optical fibres are long, flexible, transparent cables that can send large amounts of information in the form of pulses of light or infrared radiation. These light pulses are totally internally reflected along their length, due to its boundary.

Card 3

Front

How do we read CDs using lasers?

Back

Preview of the front of card 3

Card 4

Front

What is wireless technology?

Back

Preview of the front of card 4

Card 5

Front

What happens at total internal reflection?

Back

Preview of the front of card 5
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