p13 Flashcards
what ar electromagnetic waves?
transverse waves that transfer energy from the source of the waves to the absorber.
they can travel through a vacuum
order of em waves - long to short wavelength
radio waves
mictrowaves
infrared
visible light
ultraviolent
x rays
gamma rays
what are radiowaves
- longest wavelength, lowest energy
- can pass easily through air, and through many solids
- in television and radio
what are microwaves
- pass easily through air.
- satellite communications, cooking food
- they can heat up water, so could heat you up internally
how are microwaves used to heat up food?
they heat up water molecules in the food. the energy carried by the waves turn into thermal energy in the food
infrared rays
- can easily penetrate air, but are stopped by most solids, but they can also penetrate glass
- electrical heaters, cooking food, infrared cameras
- absorbed by the skin which then heats up, too much can cause burns
visible waves
- makes up all the ligt that our human eye can see
- used in fibre optic communications
ultra violent waves
- cannot penetrate through most solids or clothing but penetrate through air easily
- used in sunbeds, energy efficient lamps
- hazards include damage to eyes, mutations leading to skin cancer.
x rays
- very penetrating, air and low density materials like body tissue
- medical imaging and treatments
how many mSv in Sv
1000
what is radiation dose?
a measure of the risk of harm resulting from an exposure of the body to the radiation.
what are harms of x rays and gamma rays?
they are ionising radiation that can cause the mutation of genes and cancer.
how can radiowaves be produced?
by oscillations in electrical circuits
what happens when radiowaves are absorbed?
they may create an alternating current with the same frequency as the radio wave itself, so radiowaves can themselves induce oscillations in an electrical circuit.
