P2 - Radiation And Life

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What is light a type of?
Electromagnetic Radiation
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What is radiation?
It is a transfer of energy
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What are the 7 types of electromagnetic radiation?
Radio waves, Microwaves, Infrared, Visible Light, Ultra Violet, X-rays and Gamma Rays
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What is a photon?
A 'packet' of energy
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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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How does the frequency increase on the electromagnetic spectrum?
The frequency increases as you go
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What EM radiation has the lowest frequency?
Radio waves
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What EM radiation has the highest frequency?
Gamma rays
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What is an object that emits EM radiation called?
They are called a source
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What speed can EM radiation travel through a vacuum?
300 000 km/s
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What 3 things can happen to radiation once it has been emitted?
It can be transmitted, reflected or absorbed
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What are objects that absorb radiation called?
They are called detectors
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How do you work out the total energy of the photons transferred?
Total energy=number of photons X energy of each photon
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What units is intensity measured in?
W/m2 (Watts per square metre
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When can the intensity of a beam decrease?
If the distance of the source is bigger
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Why does the intensity decrease if the distance from the source is bigger?
The beam gets spread out and the beam gets partially absorbed
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Which 3 EM radiation causes ionisation?
Ultra violet, x-rays and gamma rays
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What is ionisation?
When a photon has enough energy to remove an electron and change the atom or molecule
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Why is ionisation dangerous?
It can damage your DNA molecules, which can cause mutations. This usually causes cancer
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How can you protect yourself from UV radiation?
Through physical barriers such as clothes or sunscreen.
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How can you protect yourself from x-rays?
By using lead shields or aprons can be worn.
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What can non-ionising radiation cause and why?
Heating up because they do not have enough energy to ionise
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How do microwaves work?
They make particles vibrate and heat up.
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Why do microwaves have a metal case and screen?
To absorb the radiation
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Why do some people think that there are health risks with microwave radiation?
Because your body absorbs the radiation, which some people believe causes cancer. But there is no conclusive evidence
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What does the earth's atmosphere do?
It filters out certain radiation from the sun by absorbing and reflecting it.
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Which 2 radiations easily pass through the atmosphere?
Visible light and radio waves
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How does the Earth warm up and what happens with the radiation?
The Earth atmosphere absorbs the radiation and then some is emitted back into space.
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Which radiation is emitted from the earth?
Infra-red radiation
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Which gases absorb the infra-red radiation?
Carbon dioxide, methane and water vapour
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Describe the greenhouse affect.
The greenhouse gases absorb the infra-red raditation and then the gases re-radiate the heat in all directions. So the gases act as an insulating layer.
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What does the ozone layer protect us from?
It protects us from too much UV radiation
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How many atom are in a molecule in the ozone layer?
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What happens when there is a loss of ozone molecules?
It creates holes
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Which 3 processes return CO2 to the atmosphere?
Respiration in plants and animals. Respiration in decomposers. Burning.
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What process removes CO2 from the atmosphere?
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What does the carbon cycle do to atmosphere?
It had kept CO2 almost at a constant for thousands of years
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Why have humans been adding more CO2 into the atmosphere?
People's lifestyles have changed, by people using more electricity. Population rising causes trees to be cut down in order to make room.
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Which gas is thought to be linked to global warming?
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What has caused global warming?
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What are climate models?
They are computers that evaluate the changes in the climate. This helps scientists to understand climate change.
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What are the consequences of global warming?
Rising sea levels, melting ice caps, more extreme weather and less food production
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Which 3 EM radiations are used to transfer information?
Infra-red, Microwave and radio
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What is infra-red radiation used for?
TV remote controls and 'night vision' cameras
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What are microwaves used for?
Mobile phones and satellite communications
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What are radio waves used for?
TV $ Radio transmissions and radar
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What are radio waves and microwaves good at and why?
They are good at transmitting information over long distances because they don't get absorbed by the Earth's atmosphere
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Why are satellites made of metal?
Because the microwaves would be reflected, this means that the dish can now focus on the wave it receives, rather than just absorbing it.
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What 2 waves are used in optical fibres?
Infra-red and light
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How do optical fibres work?
They work by bouncing waves off the sides of a thin inner core of glass or plastic. It doesn't weaken because the glass doesn't absorb much of the radiation
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What are the 2 signals that information can be converted to?
Analogue and digital
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What is an analogue signal?
A signal that can have any frequency or amplitude
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What is a digital signal?
Can only usually take 2 value.
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What happens to a signal on the 'journey'?
They often weaken as they travel, so they need to be amplified. They can also pick up interference
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Which signal is better quality and why?
Digital because they can't pick up any inteference
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Other cards in this set

Card 2


What is radiation?


It is a transfer of energy

Card 3


What are the 7 types of electromagnetic radiation?


Preview of the front of card 3

Card 4


What is a photon?


Preview of the front of card 4

Card 5


What does the amount of energy carried by a photon depend on?


Preview of the front of card 5
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