radiation and life Flashcards
whats the order of the electromagnetic spectrum?
radio waves, microwaves, infrared, visible light, ultra violet, xrays, gamma rays
what are photons?
packets of energy
how do solar cells produce electricity?
absorbing electromagnetic radiation from sun and transfers energy to electrical energy
what is the decrease in the intensity of radiation with distance due to?
(3 answers)
- photons spread out as they travel
- some photons absorbed by particles in the substances they pass through
- photons are reflected and scattered by other particles
how can radiation damage living cells?
- damage the skin eg skin burn
- age the skin, + mutate DNA, lead to cancer
- diff amount of exposure can lead to diff effects eg high intensity radiation can destroy cells leading to radiation poisoning
what are the physical barrier used to protect people from radiation?
- lead screens
- sunscreens + clothing absorb ultraviolet to prevent skin cancer
- nuclear reactors encased in thick lead + concrete
whats the ozone?
ozone is thin layer of gas in earths upper atmos, absorbs uv from sun + protects living things from harmful effects
what does light radiation from the sun do?
- warms earths surface when absorbed
- used by plants for photosynthesis
what does the energy from uv cause?
chem changes in upper atmo when absorbed by ozone layer, changes = reversible
whats the greenhouse effect?
1) earth warms up when absorbed radiation from sun
2) infrared cools down and may pass into space, reflect off clouds or radiate back from gases which absorb it
3) when earths radiation is absorbed or reflected back, this keeps earth warmer
GREENHOUSE EFFECT
what are the names of the greenhouse gases?
- carbon dioxide
- methane
- water vapour
what is global warming and the effects of it?
greenhouse effect increasing the average temp worldwide
effects:
- climate change - crop may not grow in some regions
- rising sea levels - melting glaciers, flood low lying land
- extreme weather - hurricanes
what do computer models show?
computer models predict effects of global warming + patterns in the causes
show:
- main factor = rise is co2, human activity to blame
- increased convection and water vapour in hotter atmosphere, increasing wind speed + extreme weathers
what is the carbon cycle?
- co2 in atmosphere absorbed by plants 4 photosynthesis + releases by organisms as they decompose + respire
- co2 increasing bc human activity eg burning fossils and deforestation
- burning fossil fuels releases carbon
- burning forrests reduces # of plants removing co2 from atmosphere
what is a carrier wave?
info can be superimposed onto an electromagnetic carrier wave to create signal
whats AM and FM?
the amplitude or frequency is changed by the input signal
what are analogue signals?
varies in exactly same way as info its carrying, they have almost any value
what are digital signals?
info can be transmitted digitally
signal converted into digital code that uses 0 and 1, transmitted as series of short bursts of waves called pulses
how are pulses produced?
switching the electromagnetic carrier wave on or off
what can both digital and analogue signals do?
- become weaker as they travel, so may have to be amplified at selected intervals
- pick up random variations which reduce quality of sound
why can digital signals travel longer distances at a higher quality than analogue signals?
- analogue has a diff values so hard to distinguish between noise and original so noise cant be removed
- digital has 2 states, 1 or 0 so recognised despite noise being picked up, interference can be removed
how do you store information?
digital - bytes
builds up images from pixels,
colour and brightness of each pixel set by binary digits
increasing binary digits, increases sharpness of image
builds up sound from rapid series of values called samples
increasing binary digits, increases sound quality
what are the advantages of using digital signals?
- info can be stored eg memory card
- info can be processed by comp eg spell checking, photo/music editing
how can digital pictures be used to processed and store information by computers?
- store on hard drive, cd
- photo editing manipulate images
how can music in mp3 format be used to processed and store information by computers?
- removed noise, amplify signals
- store on hard drive
what are the properties and uses of radio waves?
used for transmitting radio and tv programmes bc arent strongly absorbed by atmos
what are the properties and uses of microwaves?
microwave frequencies absorbed by water mol so used to heat objects containing water
arent strongly absorbed by atmos so can carry tv signals
what are the properties and uses of infrared and visible light?
travel huge distances down optic fibres without becoming weaker so useful for carrying info
easily booted at intervals along optical fibre
what are the properties and uses of xrays?
absorbed by dense mat so used to produced shadow pics of bones + see inside luggage at airport
