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 energyA 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)

IonisationUltra 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 escapingHealth 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 atmosphereThe Ozone layer prevents us

from too much UV Radiation:UV Radiation splits O2 into O1

molecules which joins with an O2 molecule to make O3, ozone.

When O3 absorbs UV Radiation it splits into O2 and O1 again so the reaction is reversible.

The Carbon cycleMethane and oxygen both

contain carbonHumans 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 changeGlobal warming has been caused by the

upsetting of the greenhouse effectSince we started burning more and more

fossil fuels CO2 levels have gone upGlobal warming is a type of climate

changeThe consequences of global warming are

serious:◦Sea level rising◦More floods, rain and storms◦More extreme weather

EM Waves and CommunicationInfrared:

◦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