P2: Radiation and life

P2: Radiation and life

1. Electromagnetic radiation

   • EM Spectrum
     • Gamma
       • x-rays
         • Ultra violet
           • Visible light
             • Infarred
               • microwaves
                 • Radio waves
   • What happens if radiation is absorbed...
     • Heat materials
       • microwaves
       • infarred
       • visible(laser)
     • Initiate chemical reactions
       • UV
       • Visible(laser)
     • Ionise
       • UV
       • X-rays
       • Gamma
   • Travels at 300,000 km/s(same as the speed of light in a vacuum)
   • EM radiation has a wave nature
     • As a wave it has characteristics(wavelength, frequency + wavespeed)
     • These waves don't involve matter so it can travel through a vacuum
   • Equations
     • Wave speed = frequency x wavelength
     • Wave speed = distance/time
   • Photons
     • Small packets of energy
     • Photons deliver different amounts of energy
       • Radio wave photons contain least energy
       • Gamma rays have photons with the highest amount of energy
     • A higher frequency of EM radiation means more energy is transferred by each photon
     • Intensity: is the amount of energy arriving at a square metre of surface each second
     • An increased distance from the source means the number of photons that reach the detector decrease
       • Because radiation has to travel through a medium(air, water,etc) meaning some of the photons are absorbed
   • Other information
     • Principal frequency is the frequency that an object emits
     • Microwaves are used as they are largely absorbed by water and fat molecules
       • This makes atoms unstable and to become stable again they emit infarred radiation(heating food)

2. Why scientific ideas are not excepted immediatly

   • Other more reasonable explanations for same observation
   • Scientific background can influence how they think
   • Different people interpret the same thing in different ways
   • ideas need to be peer reviewed first
   • Lots of repeating the same test trying to get the results(if possible)
   • If results can not be tested they may not be reliable

3. Issues with radiation

   • Microwave radiation can damage the brain
     • Because the brain is made of water and fat the microwaves cause infarred as heat to be emitted resulting in tumours and cancer
   • A child's brain is more likely to be affected by microwaves
     • The skull is thinner so there is less dense bone to absorb the radiation so it can reach the central brain structures
   • Phones are not to bad as people are only exposed for a short period of time

4. Ozone

   • The sun emits infarred, visible light + UV
   • UV radiation is absorbed by the ozone layer
   • The ozone layer is made up of gases and oxygen at 30 km in the stratosphere
   • When UV radiation is absorbed it breaks up the ozone into oxygen molecules and a free oxygen
   • There is still an ozone because the chemical change is reversable
   • CFC's break up the ozone producing holes in the ozone
     • CFC's
       • Found in old fridges
       • Or from aerosol cans
       • CFC's are Chlorofluorocarbons
   • Holes in the ozone means UV radiation can reach the earth's surface(mostly over north and south poles)

5. Ionisation

   • A process of removal of electrons from an atom (becomes an ion)
   • Effects of ionisation on living matter
     • Damage DNA
       • DNA no longer works in its original way
         • Cells die
         • Uncontrollable multiplication of DNA and cell division (tumour/cancer)
         • If DNA in sex cells is damaged can result in birth of a child with defects

6. Casual links

   • Correlation but no cause and effect
     • An increased amount in ice cream sales in the summer and the rise in hayfever suffers
       • There is a correlation but more ice cream does not result in more hayfever suffers
   • Cause and effect
     • More times you have and x-ray the more likely of getting cancer
       • This has a causal link as the more x-rays you have results in an increased chance of cancer as you are subjected to a higher intensity of radiation for a longer period of time

7. Transmitting data

   • EM radiation can be used for transmitting information as it can not be altered by the surrounding area and it is weakly absorbed by the atmosphere
   • Digital
     • Binary (0 and 1 or on and off)
     • Benefits
   • Analogue
     • Variety of letters, numbers, sound + colours