Flashcards
P2 facts test
Flashcards do conjunto (27)
- 1In the general model of electromagnetic radiation what does the source do?Emit
- 2In the general model of the electromagnetic radiation what does the e-m radiation do when it hits an object?Reflects, Transmits or absorbs
- 3How do e-m waves carry and transfer energy?In photons
- 4List the 7 types of elector-magnetic radiation in order of low energy to high energyradio waves - microwaves - infrared - visible light - ultraviolet - x-ray - gamma rays
- 5Which has the highest frequency and shortest wavelength?Gamma rays
- 6Why do gamma rays have such high energy?Photons are high energy and there are lots of them per second (high frequency)
- 7what speed do ALL e-m waves travel at?300,000 km/s
- 8What does the term intensity mean?The strength of the radiation; units = W/m squared
- 9What happens to intensity when you move away form the source of an e-m radiation?It gets weaker because the photons spread out over a wider area (and some radiations get absorbed)
- 10What does the term IONIZING mean?E-m waves have enough photon energy to knock out electrons, creates IONS and cause chemical reactions and cell mutations e.g. cancer or cell death
- 11Which type of e-m waves can cause ionization?high energy ultraviolet radiation
x-ray
gamma ray - 12How do microwave ovens work?Microwaves are strongly absorbed bu water molecules and used to heat food containing water
- 13What safety device are on a microwave oven?Metal cases and door screens reflect or absorb the microwaves and protect users; auto cut-off on door
- 14why could mobile phones be dangerous to user?Microwave signals could heat up the water in the brain causing damage (especially to developing brains)
- 15what does the ozone layer do?Protect humans by absorbing harmful ultraviolet radiation emitted bu the sun. This produces chemical reactions in this part of this part of the atmosphere e.g. ozone -> oxygen
- 16What are dangers of UV radiation an dhow can you protect yourself?dangers: sun burn; skin cancer; premature ageing of skin; eye cataracts
protection: clothing; sun screen; uv sunglasses; limit exposure time - 17How do x-rays work?bone and metal are dense and absorb x-rays; so that part of the film stays white
Skin and flesh are less dense so x-rays pass through them and turn the film black - 18How are radiographers protected?Lead aprons; concrete walls - lead and concrete are dense and absorb x-rays
- 19What is the green house effect?uv radiation is emitted by the sun and warms the Earth's surface when it is absorbed
The earth emits infrared radiation emitted by the sun
Infrared radiation is the trapped by green house gases in our atmosphere - 20What are the main greenhouse gases?Carbon dioxide, water vapour and methane
- 21In the carbon cycle, how is carbon added to and removed from the atmosphere?Remove carbon dioxide from the atmosphere- photosynthesis of plants and trees
add carbon dioxide to the atmosphere- respiration of humans and animals; burning fossil fuels - 22What is the evidence and what are the results of global warming?Impossible to continue growing food crops e.g. areas become deserts
More extreme weather events e.g. floods, hurricanes due to increase convection and water vapour in hotter atmosphere
flooding in low lying land due to rising sea levels - 23Why are radio waves and microwaves to carry radio and tv signals ?they are not too strongly absorbed by the atmosphere
- 24why are light and infrared waves used to carry information along optical fibersThese waves travel large distances through glass without being significantly absorbed
- 25What are the main differences between analogue and digitaldigital:
two values are 0 or 1
noises/ interface easy to clean up
carry more information per second
can be stored and processed easily by computers
analogue:
can take any value and varies continuously
noise and interface is hard to clear up - 26how are digital signals carried by e-m waves?The e-m waves are switched off or on (0 no pulse and 1 pulse)
- 27what can be stored by digital signals?sound, text, pictures and videos - need more bytes for higher quality
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- GCSE Science FlashCards sobre P2 facts test , criado por gena.hotaj em 31-05-2016.
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