Uses Of Radiation Flashcards
what can food be irradiated with
- a high does of gamma rays which will kill all microbes
- this means that food doesnt go bad as quickly as it would do otherwise
what can medical equipment be sterilised using gamma rays in preference of
boiling it
why is irradiation a good method for sterilising
- because unlike boiling
- it doesnt involve high temperatures
- so fresh fruit and plastic instruments can be totally sterilised without being damaged
what does the radioactive source for irradiation need to be
- very strong emitters of gamma radiation
- with a reasonably long half life so that it doesnt need to be replaced too often
how is beta radiation used in thickness control
- you direct radiation to the paper being made
- put a detector on the other side connected to a control unit
- when the amount of detection changes
- it means the paper is coming out too thick or too thin
- so the control adjusts the rollers to give the correct thickness
why does the radiation source for thickness control need to be beta
- because the paper will partly block the radiation
- if it all goes through or none of it does, the reading wont change
- so the thickness would never change either
how does thermal imaging work
- infrared is given out by hot object and the level changes depending on heat
- infrared cameras can be used to detect infrared radiation and monitor temperautre
- camera detects IR radiation and turns int into an electrical signal
- which is displayed on a screen as an image
- this is called thermal imaging
how do electric heaters work
- electric heaters contain a long piece of wire that heats up when a currents flows through
- the wire emits lots of IR radiation and a little visible light
- emitted radiation is absorbed by objects and air in the room
- energy is transferred by the IR waves to the thermal energy stores of the objects, causing their temperature to increase
how do optical fibres work
- they are thin glass or plastic fibres that carry data over long distances as pulses of infrared radiation
- they usually use a single wavelength of dispersion
- which can other wise cause some information to be lost
- they use internal reflection to send lots of data over long distances
what is fluorescence and how does it work
- it is a property of certain chemicals
- where ultraviolet radiation is absorbed and then visible light is emitted
- this is why fluorescent colours look so bright, as they emit light
what do fluorescent light emit and why
- they emit UV light
- they are energy efficient so they are good to use when light is needed for long periods
what are two uses of ultraviolet light and how to they work
- security pens can be used to mark property
- under UV light the ink will glow, but is invisible otherwise which helps to identify stolen property
- bank notes and passports use a similar technique to detect forgeries
- genuine notes and passports have special markings that only show up under UV light
what are radiographs in hospitals used for
- taking x ray images to help doctors diagnose broken bones
- x rays are transmitted by flesh but are absorbed by denser material like bones or metal
how are x ray images produced
- x ray radiation is directed through the object or body onto a detector plate
- the brighter bits of the image are where fewer x rays get through
- which produces a negative image (the plate starts off all white)
- x rays are also used in airport security scanners to detect hidden objects that cant be detected with metal detectors
