P2- Radiation and Life

Electromagnetic Radiation Electromagnetic radiation transfers energy is ‘packets’ (photons) Each photon carries energy, the amount of energy depends on the frequency of the radiation.

EM Radiation and energy A source = anything that emits EM Radiation. Eg: In a vacuum all radiation travels at the same speed: the speed of light (300,000 km per second) Radiation can be: ◦ RAT (Reflected, Absorbed or Transmitted)

Ionisation Ultra Violet, X Rays and Gamma rays have enough energy to ionise. Ionisation is when a photon hits an atom or molecule it sometimes has enough energy to remove an electron. If your cells are exposed to ionising radiation DNA Molecules can mutate causing cancer. (Protection includes sun cream- UV rays and lead shields- X Rays)

Microwaves (Microwave ovens and mobile phone masts) Microwave Ovens: ◦ Make water molecules vibrate heating them ◦ Can come in different power ratings ◦ Metal cases and screens reflect and absorb microwaves to stop them escaping Health Risks of Microwaves: ◦ When you make a call the phone emits radiation which could lead to long term problems ◦ People who live near phone masts may also be at risk

EM Radiation and the atmosphere (1)

EM Radiation and the atmosphere (2)

EM Radiation and the atmosphere The Ozone layer prevents us from too much UV Radiation: UV Radiation splits O 2 into O 1 molecules which joins with an O 2 molecule to make O 3, ozone. When O 3 absorbs UV Radiation it splits into O 2 and O 1 again so the reaction is reversible.

The Carbon cycle Methane and oxygen both contain carbon Humans are upsetting the carbon cycle: evidence for this can be provided by supercomputers Our life styles have changed: we use more fossil fuels etc producing more greenhouse gases

Global warming and climate change Global warming has been caused by the upsetting of the greenhouse effect Since we started burning more and more fossil fuels CO 2 levels have gone up Global warming is a type of climate change The consequences of global warming are serious: ◦ Sea level rising ◦ More floods, rain and storms ◦ More extreme weather

EM Waves and Communication Infrared: ◦ Used in optical fibres(as well as visible light) ◦ TV controls and night vision cameras Radio: ◦ Radio and TV transmissions ◦ Good at transmitting waves over long distances, don’t get absorbed as much by the earths atmosphere. Microwaves: ◦ Satellite communication ◦ Mobile phone transmissions

Analogue and Digital signals Digital signals are easier to understand even with added ‘noise’ The amount of info used to store a digital image or sound is measured in bytes. The more bytes the better the quality