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Flashcards in P2 Deck (18)
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what is the electromagnetic spectrum?

the range of radiation on earth



what is the speed of light?



What is ionisation?

this is where atoms lose an electron and become negatively or positively charged


Which types of radiation cause isonisation?

ultraviolet light


Gamma rays


What are the effects of ionising radiation?

- damage human cells 

- cause them to die or become cancerous


How do people protect themselves from x-rays?

x-rays cannot be absorbed by dense materials

people stand behind lead or concrete screens


How do microwaves damage cells?

waves heat up water in the cells damaging them

as molecules are good at transferring microwaves into thermal energy

as waves absorbed

cause water in molecules to heat up and may damage the cell


What are microwaves used for?

heating water in food

the walls and doors absorb or reflect the waves in the micro waves

also low intensity micro waves used in phones

no evidence of harm


What can over exposure to ultraviolet light cause?


sunburn, skin cancer


How can sunburn or skin cancer be prevented?

where clothes or use suncream

also these waves are blocked by the ozone layer

so strenghing that will help


How is ultraviolet light absorbed by the ozone layer?

Ozone is O3 and the ultraviolet light breaks down the ozone into oxygen 

the radiation is absorbed and the free oxygen molecule

can join up with other oxygen atoms to make ozone again


What has damaged the ozone layer/

CFCs which are released from fridges and deoderent

these covert ozone into oxygen which allows the ultraviolet radiation to pass through the atmosphere


What can some electromegnetic waves be used for?

communication- radio and microwaves

as they cannot be absorbed by air

long distance internet connection-infared and visible light



What is an analogue signal?

-this is a signal that can have any value

varies continuously

like sine wave


What is a digital wave?

this wave can only be a 0 or a 1

0=off 1=on


How is digital information stored?

stored in bytes

bytes= a string of eight binary digits

more binary code the greater the quality of the information

easily stored in electronic memories of computers


What are the advantages of digital transmission?

- information can be processed by microprocessors in phones or computers

- information can be transported faster

- can be stored in electronic memories which take little space

- information does not lose quality

analogue loses quality as it pick up noise

the signal is only amplified to improve quality while digital is processed through a renegerator which removes the noise