Karteikarten
P1 Topic 4
Karten in diesem Stapel (20)
- 1What can light signals travel through?Optical fibres
- 2How can optical fibres carry data?Over long distances as pulses of light
- 3How does light travel through an optical fibre?The ray of light enters the fibre so that it hits the boundary at an angle greater than the critical angle for the material. This causes total internal reflection within the core. The pulse of light is
reflected again and again until it emerges at the other end - 4Name 3 advantages of using lightIt quick, lots of different signals can be transmitted down a single optical fibre at the same time, little interference
- 5Name 3 properties of lasersAll waves in a laser beam have the same frequency, produces an intense beam, the beam is narrow and stays narrow
- 6How do CD players use lasers to read digital information?The surface of a CD has billions of shallow pits cut into it, the areas between the pits are called lands. The laser beam is reflected from a land and a pit slightly differently.
- 7Name 3 uses of infrared radiationCooking, remote controls and security systems
- 8How can IR signals control remote controls?Remote controls emit pulses of IR to control electrical devices, the pulses act as a digital code. The device will detect the code and follow the coded instruction
- 9Name 2 disadvantages of using IR signals to control electrical equipmentYou need to be close to the device you are operating and you have to point the beam straight at the detector
- 10What are radio and microwaves good at?Transferring information over long distances
- 11How does long-wave radio communicate?By Diffracting around the curved surface of the Earth
- 12How does short-wave radio communicate?By reflecting off the ionosphere
- 13What can make a difference to signal strength?Diffraction
- 14How can refraction help radio waves travel further?When refraction happens high up in the atmosphere it can help waves travel further for long distance communication
- 15How are waves with a lower frequency transmitted?They are refracted very quickly back to Earth
- 16What are microwaves used for?Satellite Communication
- 17How are microwaves used for satellite communication?The signal from a transmitter is transmitted into space and picked up by the satellite receiver dish which transmits signal back to Earth in different directions
- 18How are microwaves used for mobile phone communication?The transmitters pass signals between each other then back to your mobile phone
- 19What do EM receivers do?They collect the information from the EM waves
- 20Why do radio waves need the biggest receivers?Because they have the longest wavelength of all the EM waves
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- Karteikarten am P1 Topic 4, erstellt von jade16 am 18/01/2015.
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