SCIENCE

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  • Created by: amal_umar
  • Created on: 14-05-16 08:20
Whenver a wireless signal travels through the air....
it can be reflected and refracted by layers in the atmosphere. This allows a signal to be reached that would otherwise be blocked by buildings and hills
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Cons of wireless signals?
They can lead to a drop in quality. The signal can loose too much energy and become weak.
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Long distance communication, it is possible to...
reflect and refract RADIOWAVES in long distance communication from a layer in our atmosphere called the IONOSPHERE
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Why can't we send a signal in a straight line?
the earths curvature gets in the way.
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One problem with long distance communication?
When the waves are transmitted from dihes, some of the signal DIFFRACTS instead of travelling in a perfectly straight line, leading to a drop in quality.
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Another problem with long distance communication?
waves refreact as they pas through different layers in the atmosphere, leading to a drop in quality.
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What infrared signal does a remote control use?
Digital signals
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How does a remote control work?
Digital codes control different functions. Each function has a different code. When a button is pressed, the code is transmitted to the tv as a series of flashes.
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Advantages of digital signals?
Noise interference affecting signal can be removed. Can be MULTIPLEXED.
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DAB radio advantages
More stations available. Less chance of interference.
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DAB radio disadvantages
sound quality sometimes not as good as FM, sound is compressed. Not all areas of UK covered
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What are microwaves used for (not cooking)
Transmit data over large distances that are in line of sight.
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Why do microwave signals have poor signals?
Some areas are not in line of sight.
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In a CD,
bottom surface contains billions of pits. Pits store info digitally. Laser light reflected by pits when CD spins. reflected pulses of light turned into electrical signals.
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Intense coherent laser beam
Waves have the same frequency and low divergence
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Adaptations: long axon
Make connections from one part of the body to another
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Adaptations: insulating sheath
speeds up never implulses
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adaptations:: dendrites
to allow a single neurone to ACT on man fibres.
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Sensory neurones
carry never impulses from RECEPTORS to your BRAIN
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Relay neurone
makes connections between neurones in your SPINAL CORD & BRAIN
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Motor neurones
carry nerve impulses from your brain to your MUSCLES AND GLANDS
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Iris (coloured part) and cornea:
Iris controls amount of light entering the eyes. the Cornea reflects light
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Lens
focuses light onto retina so rays converge at a single point and produce a clear image on the retina.
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Retina
Contains light sensitive receptor cells. These light sensitive receptor cells cause nerve impulses to pass along sensory neurones in the optic nerve to your brain.
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Other cards in this set

Card 2

Front

They can lead to a drop in quality. The signal can loose too much energy and become weak.

Back

Cons of wireless signals?

Card 3

Front

reflect and refract RADIOWAVES in long distance communication from a layer in our atmosphere called the IONOSPHERE

Back

Preview of the back of card 3

Card 4

Front

the earths curvature gets in the way.

Back

Preview of the back of card 4

Card 5

Front

When the waves are transmitted from dihes, some of the signal DIFFRACTS instead of travelling in a perfectly straight line, leading to a drop in quality.

Back

Preview of the back of card 5
View more cards

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