PHYSICS P2

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  • Created by: TJGroves
  • Created on: 06-04-14 14:26
What is light?
A type of electromagnetic radiation
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What is radiation?
A transfer of energy
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what are the 7 types of radiation?
Radio / Micro / Infrared / Visible / UV / X-Ray / Gamma
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what is energy delivered as?
Photons (Packet of energy)
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What are the to ways light can be thought of?
As a wave (reflection) and a photon (for energy transferred)
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What does the amount of energy carried by a photon depend on?
The frequency of the radiation
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Does photon energy increase or decrease as you go along the EM spectrum?
it increases as you go along the EM Spectrum
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Which type of EM radiation has the lowest frequency and photon energy?
Radio Waves
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Which type of EM radiation has the highest frequency and photon energy?
Gamma Rays
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What can all types of EM radiation travel through?
A vacuum
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What is an object that emits radiation called?
A source
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What is the speed of light?
300,000 km/s or 3.0x10(8) m/s
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What are the 3 things that can happen when radiation reaches some matter?
Transmitted (just keep going) Reflected (bounce back) Absorbed (taken in)
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What happens to intensity as distance increases?
the intensity decreases
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Equation for total energy of a photon?
Total Energy = number of photons x energy of each photon
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What does intensity of radiation mean?
how much energy arrives at each square metre of surface per second
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What are the units for intensity
W/m(2) watts per square metre
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Why does intesity decrease?
The beam spreads out / Beam gets partially absorbed
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What is ionisation?
When a photon with a lot of energy hits a molecule and removes an electron
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What happens to the changed molecules?
They can initiate other chemical reactions
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What types of radiation are ionising?
UV / X-Ray / Gamma
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What can happen if your cells are exposed to ionising radiation?
can cause mutations in DNA and when the cell divides it is passed on, this is cancer
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What happens in radiation sickness?
Very high doses kill cells altogether
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What type of radiation does the sun emit? and how can it harm us?
UV / sunburn or even skin cancer
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What happens if you have increased exposure?
The more you're exposed the more damage it causes
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How can you protect against UV radiation?
Physical barriers such as clothes or sunscreen
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How to protect against X-Rays?
Radiographer might use lead shields over your body / wear lead aprons or behind concrete
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What types of radiation cant ionise?
Visible / Radio / micro / infrared
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What do these types do instead?
Heat molecules up
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Why do they heat molecules up?
Doesnt have enough energy so the energy is just transferred to molecules and heats them up
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What does a microwave do to things?
Makes particles vibrate and heats them up
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Why are people worried about using microwaves?
People are worried they could cause harm to people who live close to phone masts
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What does the gas ozone do?
Absorbs UV radiation
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Draw the reaction for how ozone is formed.
.
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Draw the carbon cycle
1 arrow down 3 arrows up
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how are humans effecting the carbon cycle?
changes in lifestyles / needs of more resources
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What is the problem with these different lifestyles?
Trees are chopped down
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What is the problem if plants are cut down?
Less carbon dioxide is removed from the atmosphere
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What happens if we upset the greenhouse effect?
Leads to Global Warming / change in weather patterns
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What is there a link between to suggest global warming is happening?
link between concentration of C02 and global temperature
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What are the consequences of global warming?
Ice caps melt -> Flooding -> Changed weather patterns -> Extra heat -> Problems with food production
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What types of EM radiation can transmit informaion?
Infrared (TV remotes/'night vision' cameras) Microwave (Mobile phones/satellite communication) Radio (TV, radio transmissions)
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How do optical fibres use infrared and light?
Bounces waves off thin inner core of glass / enters one end and reflects until it appears at other end
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Why are optical fibres useful?
can transmit information with signal weakening because not much is absorbed
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What happens before ending information?
It's converted into an electrical signal
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What are the two types of signals?
Analogue or digital
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Talk about features of analogue signal.
Amplitude and frequency vagaries continuously
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Talk about features of a digital signal.
Can only be two discrete number e.g. 0 or 1/easier to distinguish
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Why are digital better than analogue?
Noise is less of a problem / Can be cleaned up easily / higher quality / easy to process
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Other cards in this set

Card 2

Front

What is radiation?

Back

A transfer of energy

Card 3

Front

what are the 7 types of radiation?

Back

Preview of the front of card 3

Card 4

Front

what is energy delivered as?

Back

Preview of the front of card 4

Card 5

Front

What are the to ways light can be thought of?

Back

Preview of the front of card 5
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