Light and Lasers P1d

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How was light sent used as a means of communication?
By signals sent in the form of Morse code (series of on off signals) and by signals relayed between stations to cover larger distances
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Why is Morse code a digital signal?
It can be represented by a signal which only has 2 states (0- off and 1- on)
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What are the advantages and disadvantages of using light signals for communication?
It can be seen (+), transmitter and receiver must be in line of sight (-), very bright light can damage your eyes(-) and they cannot travel long distances in fibres (-)
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What are the advantages and disadvantages of using electrical signals for communication?
It's relatively cheap and easy and it uses simpler technology than the others(+), it requires a wired connection between sender and receiver(-)
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What are the advantages and disadvantages of using radio signals for communication?
They can reach receivers that are not in line of sight because of the Earth's curvature (+) and they cannot carry as much info as long wavelength signals
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What do optical fibres use?
Total Internal Reflection
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What does a transfer of light down an optical fibre depend on?
The critical angle of the incident light as the fibre uses TIR.
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What are some examples of the applications of TIR in fibre optics?
Endoscopies
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What is an endoscopy?
An endoscopy allows doctors to see inside a body without needing surgery
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How does an endoscopy work?
1. Light passes along 1 set of optical fibres to illuminate the inside of the body 2. The light is reflected by TIR 3. The reflected light passes up another set of fibres to an eyepiece/camera
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What does a laser light produce?
A narrow beam of light of a single colour (monochromatic)
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Why do most lasers produce an intense coherent beam of light?
The waves have the same frequency, have low divergence and are in phase.
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How is a laser beam used in a CD player by reflection from a shiny surface?
1. Info is stored digitally on the bottom surface of CD as pits 2. Pits represent the digital signal 3. Laser light is shone onto the CD surface and the difference in the reflection provides the info for digital signal
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Other cards in this set

Card 2

Front

Why is Morse code a digital signal?

Back

It can be represented by a signal which only has 2 states (0- off and 1- on)

Card 3

Front

What are the advantages and disadvantages of using light signals for communication?

Back

Preview of the front of card 3

Card 4

Front

What are the advantages and disadvantages of using electrical signals for communication?

Back

Preview of the front of card 4

Card 5

Front

What are the advantages and disadvantages of using radio signals for communication?

Back

Preview of the front of card 5
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