Physics Two - Radiation and Life

Radiation and life :0

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  • Created by: jac
  • Created on: 23-06-10 10:31

Light is an electro magnetic radiation

Light is a type of ELECTROMAGNETIC RADIATION - EM

Visible light (colours of the rainbow) is radiation our eyes can see

Radiation towards the red end of the rainbow is infa red radiation

The raiation towards the violet end is called ultra violet.

Radio

waves

Micro

waves

Infa

Red

Visible

Light

Ultra

Violet

X-Rays

Gamma

Rays

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Frequency

Type of electromagnetic radiation

Typical useWavelength

highest

gamma radiation

killing cancer cells shortest X-rays medical images of bones

ultraviolet radiation

sunbeds

visible light

seeing infrared radiation optical fibre communication microwaves cooking

lowest

radio waves television signals longest

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Photons

  • Em transfers energy, this is through protons
  • EM SOURCES EMIT THESE
  • each proton carries a different amount of energy depending where it is on the
    EM SPECTRUM
  • More energy if it towerds ultra violet and less if beyone infa red

Sources - Sun , radio , mobile phones etc....

Energy spreads out until it reaches a form of matter;;

Transmitted - keeps going through eg.glass

Rflected - bounces back eg.mirror These are called detectors

Absorbed - skin absorbs sun

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  • Energy given out is

TOTAL ENERGY = number of protons x energy per proton

  • intensity of radiation is how much energy arrives at a sqaure metre per second
  • Units of intensity measured in

W/m - Watts per square metre

  • Intensity of of radiation beams decrease as it moves further from source as protons spread out so less hit you
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Ionisation

  • some em radiation cause ionisation - ultra violet , x - ray , gamma ray
  • When aphoton hits an atom if it is ionising it will break the atom into bits called IONS
  • If this happens to body cells it can damage important DNA
  • it will cause mutations and cells may begin to constantly divide - causing cancer
  • We all get exposed to uv radiation from sun which can damage skin cells causing sun burn
    - or bad cases can cause skin cancer
  • You can protect by physical barriers like - Clothes - sunscreen
  • When an X - Ray is taken - un investigated body parts are coverd with lead shields to absorb radiation thats unnnecary to certain parts.
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Uses of EM radiation

  • non ionising radiation when absorbed trandefers energy to molecules and atoms - Making them heat up
  • If exposed to heat to long or a high amount - YOU BURN
  • we use this to cook food

Microwave Radiation - if exposed to it water in body could heat up dangerously why microwave ovens have metal casesand glass doors to stop there protons reaching us.

Infa Red- tv, remotes , night vision cameras

Microwave - microwaves , mobile phones , satellite communication

Radio - Tv , radios transmisions radar

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Photosynthesis

.

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Greenhouse Effect

.

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Ozone Layer

  • ozone is an oxygen molecule conatain three oxygen atoms - 03
  • Ozone happens naturally at a certain height - making the ozone layer around earth
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Climate Change

  • Green house effect of co2 naturally heating earth works to well as we are flooding our atmosphere with co2 and ch4. OVER HEATIN - GLOBAL WARMING

Consequences

  • Ice melting - causing floods, meaning land will get wet not good enough to grow crop
  • Or over heating making longer droughts, and hurricanes - To dry for crop
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