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P2 Flashcards
Cards in this deck (28)
- 1What are the seven types of EM radiation?Radio Waves, Micro Waves, Infrared, Visible Light, Ultraviolet, X-Rays, Gamma Rays
- 2What does EM radiation do? How does it do it?EM radiation transfers energy in the form of photons (packets of energy).
- 3Which EM radiation has the highest frequency?Gamma Rays
The higher the frequency, the higher the energy of the radiation. - 4How fast does EM radiation move in a vacuum?300,000 km/s
This is the same as light because light is on the EM spectrum) - 5What are the three ways that radiation can affect something?Transmission - Passes through the object
Reflection - Bounces off of the object
Absorption - The energy is absorbed by the object - 6IntensityThe amount of energy over each square metre per second.
The units are Watts per Square Metre
(W/m^2) - 7Inverse Square LawIntensity = Energy of Source / Distance^2
Intensity is inversely proportional to the distance squared. - 8IonisationThe removal of an electron from an atom or molecule caused by excessive energy.
- 9Why is ionisation an issue?It forms ions which can cause unwanted chemical reactions.
Can cause mutations that lead to tumours and cancer. - 10How is ultraviolet radiation blocked?Physical Barriers (clothes)
Suncream - 11How is x-ray radiation blocked?Lead shields and aprons
Thick layer of concrete - 12How do microwaves heat food?Microwaves caused vibration of particles. They are strongly absorbed by water which causes them to vibrate and heat up food.
Most food has water in so this makes heating food easy using microwaves. - 13Why are some people concerned with the use of microwaves?They are used in mobile phones so they are near the skull and brain.
Some people think there may be a link between cancer and microwaves.
Can cause heating of body cells (water) - 14Greenhouse EffectThe Earth absorbs infrared radiation which heats it up. Some is then emitted at a lower frequency. This is absorbed and then re-emitted by greenhouse gases which keeps the Earth warm at night.
- 15What are the 3 greenhouse gases?Water vapour, methane and carbon dioxide
- 16How does the ozone layer protect us?Ultraviolet radiation is absorbed by the O3 molecules. These then split into O2 and O which can then rejoin and continue to protect us against harmful ultraviolet.
- 17Draw and label the Carbon Cycle
- 18How are humans upsetting the Carbon Cycle?Lifestyle - Use of cars and planes releases carbon dioxide
Population - Rising population leads to need for land so trees are removed and burnt adding more carbon dioxide - 19Global WarmingA rise in the temperature of the Earth caused by the increase in greenhouse gases due to human activity.
- 20What could be the consequences of global warming?Severe, unpredictable weather
Flooding (caused by ice melting)
Food production affected by changing weather severity - 21Give 2 uses of EM radiation in transferring informationInfrared - Used in TV remotes and cameras
Microwaves - Mobile phones and satellites
Radiowaves - TV, radios and radar - 22Why are radio-waves mainly used for communication?They are not absorbed by the atmosphere
Good over long distance - 23Why are microwaves used for satellite communication?They are not absorbed by the atmosphere
Reflected by metal so can be redirected
Good over long distance - 24How are optical fibres used for data exchange?Waves can be reflected on the inside of the tube repeatedly (total internal reflection) until it reaches the end of the fibre.
Low interference
Glass does not absorb much radiation - 25How is information put onto EM radiation?It is superimposed on a carrier wave.
- 26Analogue SignalA signal with an infinite range of values that can vary continuously.
- 27Digital SignalA signal with two finite values of either on or off. Information is carried by switching the signal on or off.
- 28What are the advantages of digital signals?Less susceptible to noise distortion (two values are very distinct)
Does not need to be amplified as much
Easily used by computers
Several can be transmitted at once
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- Flashcards on P2 Flashcards, created by Finlay Boyle on 11/05/2017.
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- Finlay Boyle
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