P2 - Radiation and Life

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P2 - Radiation and Life

Caption: : Different photons in the EM spectrum have different levels of energy. Intensity also depends on the type of photon.

EM radiation can act like a wave:Transfers energyTransverse or waveformReflects, RefractsIntensity: Energy arriving over a specified area (Joules per metre squared)As you get further away from an object, the intensity drops.White light is a mixture of all the colours (different frequencies of each light section). Light and other EM radiation travels as photons.

Microwaves:Reflect off metal wallsNon-IonisingTransmit through air, glass, plasticMicrowaves of certain frequencies can be absorbed by water and some fats.Microwaves of different wavelengths don't do this and are used by mobile phones and wireless networks

Infrared:In cooking;Infrared waves transfer the heat energy from the heat source to the food, where it is absorbed.Infrared waves can be reflected from shiny surfaces.Infrared is Non-Ionising

Digital and Analogue Signals

AnalogueVarying amplitude and frequenciesUsed for cassettes and video tapesWhen a signal is sent it weakens in strength  and gains interference along the way.The receiver would amplify the analogue with the interference, but would regenerate the digital to be of the same quality as before it was transmitted.

DigitalTwo values; the wave is either on or off, which is received as either 1's or 0'sUsed for DvD's, CD's and mobile phones.The digital code is built up of bits and groups of eight called bytes. a string of 8 bits makes 256 different potential values, stored as memory.1KB = 1000B1MB = 1000,000B1GB = 1000,000,000B

Advantages of Digital

Can be processed by microprocessors Can be stored and take up little memory Carry more information than analogue signals Delivered with no loss of quality

Ozone Layer and the Atmosphere

The Sun transmits UV, visible light and infrared energy to the Earth.Some energy is reflected by the Ozone layer (O3)Most of this is soaked up by the Greenhouse Gases in the atmosphere, such as Methane (CH4) and Carbon Dioxide (CO2), but this makes up less than 1% of the atmosphere.consequences of high levels of Greenhouse GasesTemperatures rise:                             ice caps meltsea levels riselow lying areas floodCrops fail:Prices riseStarvation

The Carbon Cycle

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UV Radiation

Most UV Radiation is absorbed by the Ozone layer however some types of UV radiation reaches us on Earth.Pros Produces Vitamin D  in the skinHelps the immune systemReleases EndorphinsHelps skin conditionsRegulates circulatory systemConsSunburnPremature aging of the skinEye DamageSkin Cancer - UV is ionisingIonisation - turns neutral atoms into ions which are very reactive