P4- Radiation for Life

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  • when materials rub together, subatomic particles (electrons) transfer to the object being rubbed on
  • if you lose electrons you become positive
  • if you gain electrons you become negative
  • opposite charges attract, same charges repel 

to reduce the chance of getting a shock you can:

  • earth the applience
  • use insulation mats
  • wear shoes with insulating soles
  • bond fuel tanks to aircrafts

static electrisity can be a nuisance:

  • TV screens becoming charged atrracting dust
  • synthetic clothes cling to body

An anti-static line connects objects so they are connected to earth.

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Dust Precipitators


  • metal plates are connected to a high voltage so have a large potential difference
  • the grid and plates are oppositly charged
  • waste gases pass through the grid and gain a charge, they are then attracted to the plates
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Paint Sprayers

  • paint is attracted to the car
  • paint repels eachother so spreads out
  • when an area is painted it no longer attracts the paint
  • paint is attracted to all surfaces so front and back is painted. 
  • pros:
  • give car a more professional finish
  • less paint is wasted
  • quicker than normal work
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X-rays & Gamma Radiation

  • X-rays are produced by firing high speed electrons at an angled metal target
  • gamma is emmitted from the nuclei of some radio active atoms
  • X-rays can be dangerous if you have a high enough dosage
  • Gamma is the most penetrating so is harmful to cells and can cause cancer
  • In hospital X-rays can produce images
  • Gamma is used for radio therapy (gamma knife) + tracers & to sterlilise medical equipment 
  • Gamma knife focuses gamma onto cancerous cells. it rotates around the point giving a full dose to the cancerous cell & low doses to the surrounding areas 
  • tracers are made with short half life gamma. They are drunk or injected. A special cammera films movement of fluid in the body finding leaks.
  • Both X-rays and gamma rays are elecromganetic waves
  • an x-ray machine can be turned off but gamma is a constant production

useful video:


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Nuclear Fusion

Nuclear Fusion - fusing together of hydrogen neuclei resulting in the fromation of helium

  • producing this reaction on Earth is difficult due to the conditions needed
  • conditions- exstremly high temerature & high pressure
  • this reaction occurs naturally in stars 
  • some scientist have reported carrying out reactions at normal conditions, while others couldn't 
  • if cold fusion works, it would mean cheap, limitless electricity
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Nuclear Fission

  • Nuclear power stations work the same as fossil fuel stations but with uranium as the fuel
  • heat is produced in a reactor due to uranium decay causing a chain reaction
  • a single neutron causes uranium to split causing heat and new neutrons to be produced
  • radioactive waste is produced 
  • https://www.youtube.com/watch?v=MGj_aJz7cTs
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  • ultrasound is a longatudinal wave
  • it has a high frequency & short wave length meaning it can penetrate the human body

we can use ultrasound instead of x-rays because:

  • it produces images of soft tissue
  • it doesn't damage living cells

uses of ultrasound:

  • body scans
  • shatter kidney stones
  • measure blood flow due to the doppler effect
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Carbon Dating

  • radio active carbon can be used to date things
  • radiation comes from rocks and soil
  • older the rock, lower the uranium:lead ratio 
  • younger the rocks higher the uranium:lead ratio, this is how we date the earth
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Radiation (Alpha, Beta, Gamma)


  • nucleus of a helium atom
  • charge of 2+
  • it is unstable due to neutrons


  • its a high energy fast moving electron
  • its is less ionising
  • its is stopped by a sheet of aluminium


  • it has no charge
  • emitted at the same time as alpha or beta
  • it is stopped by concrete or lead

radiation collides with neutral atoms, altering structureby knocking off electron making them ions, when DNA is ionised, the chemical reactions stop causing cancer.

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Half Life

half life- amount of time taken for half of the atom in a sample to decay

activity- number of nuclear decays emitted per second 

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  • live wire - brown - carries high voltage
  • neutral - blue - completes circuit
  • Earth - yellow & green - prevents applience becoming live, if the live wire becomes lose & touches case, earth wire passes down current causing a surge and melting the fuse
  • cases can sometimes be double insulated - a plastic coat to prvent appliance becoming live
  • current - flow of electron
  • voltage - amount of energy transfered
  • resistance - removes energy from electrons & slows them down
  • voltage = current x resistance
  • "the current flowing through a wire is proportional to the potential difference (voltage) across it providing temperature remains constant" - Ohm's law 

pros of circuit breakers rather than fuses:

  • switch current off faster & detect smaller charges
  • easily reset & reused 
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Straight forward, can easily produce revision mind maps with this information. Thank you :)

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