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25 Cards in this Set
- Front
- Back
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What is radiation? |
A transfer of energy NOT matter |
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List the electromagnetic spectrum in order of lowest frequency |
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What is a photon? |
A packet of energy or a tiny droplet of energy |
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What can happen if radiation is emitted by a source? |
-The radiation can be transmitted like light passes through glass -it could be reflected like light reflected by a mirror -the radiation could be absorbed like sunbathe absorbing uv radiation from sun |
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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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What is a source and give examples |
Any object that emits radiation etc sun mobile phone radio transmitter |
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What happens as radiation is emitted from a source |
It spreads out until it reaches some matter |
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What are objects that absorb radiation called and give examples |
Detectors like our eyes are light detectors |
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What is intensity of a radiation |
How much energy arrives at each square metre per second |
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Why does the intensity of a beam of radiation decrease with distance |
The beam spreads out and the beam gets partially absorbed as it travels |
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What is ionisation |
When a photon hits an atom or molecule it has enough energy to remove an electron and change the atom or molecule |
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What are the radiations that cause ionisation |
Uv gamma and x rays |
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What are the dangers of ionisation in your cells? |
The damage to DNA molecules can cause mutations and the cells can start to divide over and over again without stopping causing cancer very high doses can kill your cells all together causing radiation sickness UV radiation is ionising and can cause damage to cells in your skin can lead to skin cancer and sunburn the longer you're exposed the more damage |
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How can we protect ourselves from dangerous radiation |
UV -physical barriers such as clothes sunscreen sun block x rays - lead shield lead absorbs x rays stand behind concrete |
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What happens when light is absorbed say a substance |
It transfers energy to the atoms or molecules of the substance and heats them up |
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How do microwaves cook? |
They make particles vibrate heating them up some are strongly absorbed by water molecules so can heat things containing water |
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How do microwaves combat the danger that they d might cause ? |
They have metal cases and screens over their glass doors which reflect and absorb he waves without stopping them getting out |
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Explain how the gh effect helps regulate the earth's temperature |
The earth a absorbs EM radiation from the sun this warms the earth's surface up it then emits some EM radiation back out into space cooling us down .! out to radiation emitted by earth is infrared (heat) A lot of it is absorbed by atmospheric gases CO2 methane water vapour these reradiate heat in all directions back towards the earth so the atmosphere acts as an insulating layer stopping the earth losing all of its heat at night |
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What does ozone do? |
Absorbs uv radiation |
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How is ozone made |
O2 gets split with oxygen atoms combine a to Form o3 |
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What processes return CO2 to the atmosphere? |
Respiration in plants and animals and respiration in decomposers and burning |
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What are the consequences of global warming? |
Sea level rose causing floods ice melt Changed weather patterns longer hotter droughts More wind and rain Food production |
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What are different frequencies used for |
Infrared -TV remote controls and night vision cameras Microwave -mobile phones and satellite communication Radio - TV and radio transmitter and radar |
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What's an optical fibre |
Works by bouncing waves of the sides of a thin inner core of glass or plastic The wave enters one end and is reflected repeatedly until it emerged on the other end |
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What's the difference between analogue and digital signals? |
Analogue varied it's amplitude or frequency Digital can only take one of a small number of discrete values Digital are better quality noise is easy to cent up also can transmit several sights at once so u can send a lot of info at once also digital are easy to process using computers |
