radiation and life

Question 1

whats the order of the electromagnetic spectrum?

Answer 1

radio waves, microwaves, infrared, visible light, ultra violet, xrays, gamma rays

Question 2

what are photons?

Answer 2

packets of energy

Question 3

how do solar cells produce electricity?

Answer 3

absorbing electromagnetic radiation from sun and transfers energy to electrical energy

Question 4

what is the decrease in the intensity of radiation with distance due to?
(3 answers)

Answer 4

• 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

Question 5

how can radiation damage living cells?

Answer 5

• 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

Question 6

what are the physical barrier used to protect people from radiation?

Answer 6

• lead screens
• sunscreens + clothing absorb ultraviolet to prevent skin cancer
• nuclear reactors encased in thick lead + concrete

Question 7

whats the ozone?

Answer 7

ozone is thin layer of gas in earths upper atmos, absorbs uv from sun + protects living things from harmful effects

Question 8

what does light radiation from the sun do?

Answer 8

• warms earths surface when absorbed

- used by plants for photosynthesis

Question 9

what does the energy from uv cause?

Answer 9

chem changes in upper atmo when absorbed by ozone layer, changes = reversible

Question 10

whats the greenhouse effect?

Answer 10

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

Question 11

what are the names of the greenhouse gases?

Answer 11

• carbon dioxide
• methane
• water vapour

Question 12

what is global warming and the effects of it?

Answer 12

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

Question 13

what do computer models show?

Answer 13

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

Question 14

what is the carbon cycle?

Answer 14

• 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

Question 15

what is a carrier wave?

Answer 15

info can be superimposed onto an electromagnetic carrier wave to create signal

Question 16

whats AM and FM?

Answer 16

the amplitude or frequency is changed by the input signal

Question 17

what are analogue signals?

Answer 17

varies in exactly same way as info its carrying, they have almost any value

Question 18

what are digital signals?

Answer 18

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

Question 19

how are pulses produced?

Answer 19

switching the electromagnetic carrier wave on or off

Question 20

what can both digital and analogue signals do?

Answer 20

• become weaker as they travel, so may have to be amplified at selected intervals
• pick up random variations which reduce quality of sound

Question 21

why can digital signals travel longer distances at a higher quality than analogue signals?

Answer 21

• 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

Question 22

how do you store information?

Answer 22

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

Question 23

what are the advantages of using digital signals?

Answer 23

• info can be stored eg memory card

- info can be processed by comp eg spell checking, photo/music editing

Question 24

how can digital pictures be used to processed and store information by computers?

Answer 24

• store on hard drive, cd

- photo editing manipulate images

Question 25

how can music in mp3 format be used to processed and store information by computers?

Answer 25

• removed noise, amplify signals

- store on hard drive

Question 26

what are the properties and uses of radio waves?

Answer 26

used for transmitting radio and tv programmes bc arent strongly absorbed by atmos

Question 27

what are the properties and uses of microwaves?

Answer 27

microwave frequencies absorbed by water mol so used to heat objects containing water

arent strongly absorbed by atmos so can carry tv signals

Question 28

what are the properties and uses of infrared and visible light?

Answer 28

travel huge distances down optic fibres without becoming weaker so useful for carrying info

easily booted at intervals along optical fibre

Question 29

what are the properties and uses of xrays?

Answer 29

absorbed by dense mat so used to produced shadow pics of bones + see inside luggage at airport