uses of em waves Flashcards
(14 cards)
what are radiowaves used for?
transmit radio and terrestial tv signals
why are radio waves used to transmit radio and terrestial tv signals?
they can travel long distances before being absorbed
what can short length radiowaves reflect off?
short length radiowaves can reflect off a layer of charged particles in the atmosphere (ionosphere)
what are microwaves used for?
heating food and communicating with satelittes in space
why are microwaves used to heat food?
most foods contain lots of water molecules, water molecules absorb energy from microwaves and this energy heats up food
why are microwaves used for satelitte communication?
because microwaves can pass through earth’s atmosphere without being reflected or refracted
what is infrared used for?
emitted by electrical heaters and used to cook food in ovens, and used in infrared cameras
why is infrared used to cook food?
because energy from infrared is easily absorbed by surface of objects
what is visible light used for?
communication using fibre optics, which are used to carry telephone and cable tv signals
what is uv used for?
energy efficient lightbulbs and tanning
why is uv used for energy efficient lightbulbs?
radiates least heat but more energy
what are both x-rays and gamma rays used for?
medical treatment/imaging
both x-rays and gamma rays are very penetrative, what is meant by this?
can pass easily though body tissue
why can we bones on x-ray images?
because x-rays are absorbed by bones
