Physics - P2

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  • Created by: L_Georgie
  • Created on: 24-03-16 19:10
Name the seven types of radiation in the EM spectrum from least energy to most energy.
Radio waves, microwaves, infra-red, visible light, ultra violet, X-rays and gamma rays.
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What does all electromagnetic radiation transfer?
Energy.
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What is the energy delivered as?
Photons.
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What is a photon?
A photon is a tiny 'droplet' or 'packet' of energy.
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What type of radiation has the lowest frequency and least energy?
Radio waves.
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What type of radiation has the highest frequency and most energy?
Gamma rays.
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What is the term for an object that emits radiation?
A source.
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What three things can happen once it meets some matter?
It can be transmitted, reflected or absorbed.
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What are objects called that absorb radiation?
Detectors.
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Why does the intensity of a beam of radiation decrease with the distance of the source?
It decreases because the beam spreads out and the beam gets partially absorbed as it travels.
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What is ionisation?
When a photon has enough energy that it is able to remove an electron from an atom/molecule and change the atom/molecule.
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What types of radiation are ionising?
Ultraviolet, x-rays and gamma rays.
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What happens if your body cells are exposed to ionising radiation?
It could cause the cells to mutate, and it could cause cancer. It could even kill cells altogether if the doses are really high.
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How do they doctors protect the rest of your body when you go for an x-ray?
They may put lead shields on the parts that aren't being investigated as lead absorbs the x-rays.
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How do microwaves heat up food?
Microwaves make particles vibrate, heating them up. Microwaves are absorbed by water so it heats up food containing water.
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What do the power ratings on microwaves show?
The higher the watts on the microwave the higher intensity radiation they produce.
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What feature on a microwave stops the radiation escaping and effecting us?
They have metal cases and screens on the door to reflect and absorb the radiation so it doesn't get out.
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Why do people say that phones can cause harm?
Because phones use microwaves to send signals meaning that it emits radiation and some of the radiation can get absorbed by your body heating up your organs.
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What is the Earth surfounded by?
An atmosphere.
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What do the gasses in the atmosphere do with certain types of radiation?
They filter out certain types of radiation emitted from the sun by absorption and reflecting it back into space.
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How does the greenhouse keep us warm?
The Earth absorbs the radiation given out by the sun which warms the surface of the Earth. Then some of the radiation gets emitted back into space. At night the Earth's atmosphere acts as insulation and traps the heat inside.
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What radiation does the ozone layer absorb?
It absorbs UV radiation.
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What is ozone and what does an ozone molecule contain?
Ozone is a form of oxygen. An ozone molecule contains three oxygen atoms joined together.
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How do the ozone molecules form?
UV radiation splits an ordinary oxygen molecule then one of the oxygen atoms joins with another oxygen molecule to form an ozone molecule.
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What is special about the reaction between the oxygen molecules to make ozone molecules?
It is a reversible reaction.
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What happens if we didn't have ozone?
Lots more UV radiation would reach us on Earth meaning that we will be at more risk as UV is ionising radiation.
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What puts carbon dioxide into the atmosphere?
Respiration in plants and animals, respiration in decomposers and burning things like trees and coal.
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What one process removes carbon dioxide from the atmosphere?
Photosynthesis.
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How are humans upsetting the carbon cycle?
We are putting more carbon dioxide into the atmosphere faster than it is being removed by burning more fossil fuels and chopping down trees.
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How are humans reducing photosynthesis?
We are chopping down trees in order to build more houses.
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What has upsetting the greenhouse effect led to?
Global warming.
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What can be used to explain climate change?
A climate model.
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What could the consequences of global warming be?
Rising sea levels could lead to flooding, more extreme weather, stronger winds, more rain and it could impact food production.
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What is infrared radiation used for?
TV remote controls and 'night vision' cameras.
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What is microwave radiation used for?
Mobile phones and satellite communication.
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What are radio waves used for?
TV and radio transmissions and radar.
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Why are radio waves and microwaves good at transmitting information over long distances?
Because they don't get absorbed by the Earth's atmosphere as much as most waves in the middle of the EM spectrum.
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Why are microwaves used for satellite communication?
They are used because they can pass easily through the Earth's atmosphere.
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What radiation is used in optical fibres?
Infrared and light.
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How do optical fibres work?
They bounce waves off the sides of a thin inner core of glass or plastic. The wave then enters one end of the fibre and it is reflected repeatedly until it reaches the other end.
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What values can an analogue signal take?
An analogue signal can take any value in a particular range.
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What values can a digital signal take?
A digital signal can only take one of a small number of discrete values (normally 2) like 0 and 1 or true and false.
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How are the pulses in a digital signal created?
Through switching the EM carrier wave on and off.
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Why do signals have to be amplified?
Because they weaken as they travel and they also pick up interference or noise from electrical disturbances or other signals.
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Why is noise less of a problem with digital signals than analogue?
Because if you amplify the digital signal the noise doesn't get amplified however with a analogue signal the noise does get amplified.
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Why is digital signals better than analogue?
Digital signals are higher quality, you can transmit several signals at once and digital signals are easy to process with computers.
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What is the amount of information stored in a digital signal measured in?
Bytes
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Other cards in this set

Card 2

Front

What does all electromagnetic radiation transfer?

Back

Energy.

Card 3

Front

What is the energy delivered as?

Back

Preview of the front of card 3

Card 4

Front

What is a photon?

Back

Preview of the front of card 4

Card 5

Front

What type of radiation has the lowest frequency and least energy?

Back

Preview of the front of card 5
View more cards

Comments

Hxneul._.Chan

Erm, this is P1 if this is for OCR Gateway :/

-bob-

no its p2 for edexel

Hxneul._.Chan

-bob- well, why has the author of this set used it as the OCR exam board then??

-bob-

i have no idea, they might have pressed the wrong one 

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