Cooking and communicating using waves - P1e

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  • Created by: iram_f
  • Created on: 24-09-14 18:51
What can microwaves be used for and what are some of their properties?
Microwaves are used for satellite communication, mobile phones & radar. They are absorbed by water & fat molecules, penetrating 1cm deep into food, yet can also cause burns when absorbed by skin tissue; they can travel through glass & plastics.
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What is needed to send a microwave signal?
You need to be in line of sight in order to recieve a microwave signal, which transmit information over large distances.
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How can microwave signals be affected?
They are affected by large obstacles, such as tall buildings that block signals as microwaves are not diffracted around large objects. Adverse weather, large bodies of water, the curvature of the Earth & interference between signals affect them too.
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How do microwaves transfer energy to materials?
Fat and water molecules in the outside layers of food heat up, increasing the kinetic energy of the particles, which then transfer energy to the centre by conduction or convection.
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What can infrared rays be used for and what are some of their properties?
Infrared rays are used to heat the surface of food in cooking and in remote controls - they are reflected by shiny objects and absorbed by black objects.
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What are some concerns about the use of microwaves in mobile phones?
Some think microwaves could cause ear/brain tumours, brain damage or genetic mutation in DNA, especially near phone transmission masts. Children are at risk from microwave signals as they have thin skulls. People must balance benefits with risks.
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How do infrared rays transfer energy to materials?
Infrared is absorbed by all the particles on the surface of the food, increasing the kinetic energy of the particles, which is then transferred to the centre of the food by conduction or convection.
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How can the problems caused by a loss of microwave signal be reduced?
You could limit the distance between transmitters or even position masts high on top of hills/tall buildings. Installing more satellites to reflect the signals could work too.
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Other cards in this set

Card 2

Front

What is needed to send a microwave signal?

Back

You need to be in line of sight in order to recieve a microwave signal, which transmit information over large distances.

Card 3

Front

How can microwave signals be affected?

Back

Preview of the front of card 3

Card 4

Front

How do microwaves transfer energy to materials?

Back

Preview of the front of card 4

Card 5

Front

What can infrared rays be used for and what are some of their properties?

Back

Preview of the front of card 5
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