P2
- Created by: superlouasaur
- Created on: 03-04-15 11:02
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- P2- radiation and life
- The sun
- UV radiation can cause skin cancer
- UV appears just after the violet end of the visible light spectrum
- Melanin (pigment in skin provides a little protection from UV)
- Uv radiation is part of electromagnetic radiation
- Spread out to form the electromagnetic spectrum
- Need sunlight for vitamin D
- Strengthens bones and muscles and boosts immune system
- Darker skin makes it more difficult to absorb vitamin D
- Reduces depression
- UV radiation can cause skin cancer
- Radiation models
- All radiation has a source that emits it
- It spreads out or radiates
- Visible light causes a chemical changes at the back of the eye
- Air is good at transmitting light
- Objects would be invisible if it wasn't reflected off the object
- Radiation from the sun includes infrared, visible light and UV
- Some radiation is transmitted through the atmosphere
- Most harmful UV radiation is absorbed by the atmosphere
- Life depends on the ozone layer absorbing UV radiation
- Most harmful UV radiation is absorbed by the atmosphere
- Some radiation is transmitted through the atmosphere
- The atmosphere is a mixture of gases inc oxygen
- Oxygen atoms form to make ozone O3
- When UV is absorbed it can break ozone into oxygen
- Reversible changes
- When UV is absorbed it can break ozone into oxygen
- Man made chemicals can form holes in the ozone layer that allows radiation through
- Oxygen atoms form to make ozone O3
- All radiation has a source that emits it
- Absorbing electromagnetic radiation
- When materials absorb radiation they gain energy
- Radiation can cause a varying electric current in metal wire
- Radiation can cause heating
- Radiation can cause chemical changes
- Ionisation can damage living cells
- Radiation arrives in pockets called photons
- Sources emit radiation photon by photon
- Absorbers gain the energy photon by photon
- Sources emit radiation photon by photon
- xrays, gamma rays and some UV are ionising
- When materials absorb radiation they gain energy
- X-rays
- Discovered in 1890s
- Intensity is the energy that arrives at a square meter of surface each second
- Intensity is less the further away it is
- Gamma is similar to x-rays but comes from radioactive materials
- Both used to image internal organs
- X-rays
- Discovered in 1890s
- Intensity is the energy that arrives at a square meter of surface each second
- Intensity is less the further away it is
- Gamma is similar to x-rays but comes from radioactive materials
- Both used to image internal organs
- Both used to image internal organs
- The radiation is more dangerous to quickly dividing cells (fetuses)
- Reducing exposure to radiation
- Time
- Distance
- Shielding
- Sensitivity
- X-rays
- Both used to image internal organs
- The radiation is more dangerous to quickly dividing cells (fetuses)
- Reducing exposure to radiation
- Time
- Distance
- Shielding
- Sensitivity
- Heat
- Microwave
- Uses microwave radiation to transfer energy to absorbing materials
- Water, fat and sugar are good absorbers
- Microwave doors reflect the radiation to stop the microwave radiation cooking humans
- Heating effect depends on intensity and duration/ time
- Even things with temperatures below 0 degrees c emit infrared
- Microwave
- Climate change
- Climate- average weather in a region over many years
- The Earth's average temperature is 15 degrees c
- The earth's surface absorbs radiation from the sun, this warms theearth
- The greenhouse effect
- Greenhouse gases (carbon dioxide, methane and water vapor)
- ]Absorb some infrared radiation which causes heating effect
- The carbon cycle describes the stores of carbon and processes that move carbon
- Co2 levels are rising
- Human activities cause this
- Co2 levels are rising
- The future
- Natural factors can also cause climate change
- Scientists use computer models to predict what will happen with increasing CO2 levels
- Climate changes causes:
- Extreme weather
- Rising sea levels
- Drought and desertification
- Health problems
- Poor countries won't be able to deal with the effects of climate change
- The gulf stream that keeps the UK at a mild temp may be slowing because of climate change
- Technology can be used to reduce CO2 but will take a long time to develop and put into operation
- Information
- Mobile phones use microwaves
- Radio waves of the highest frequency
- Can travel long distances because they are only weakly absorbed by the atmosphere
- Radio waves of the highest frequency
- Can also be distributed using optical fibres (high purity glass- so less is absorbed)
- Carrier wave+ information = signal
- Digital signals only require two symbols, on and off
- Continuous variation in waves is analogue
- Microprocessor in phones decode information
- Takes binary code and changes it to varying voltage which converts to noise
- Mobile phones use microwaves
- Digital signals
- Can be processed by microprocessors
- Can be stored in memories and take up little space
- Can carry more information each second
- Can be delivered without losing quality (no noise)
- Health risks
- Radiation leaving a mask is weak bythe time it reaches humans as it is spread out
- Need to judge reliability of information given to us by studies
- Look at how the sample participants are selected
- Needs to be a large sample
- Other factors
- The sun
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