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Electromagnetic waves, Medical imaging, Trasmitting Telecommunications…
Electromagnetic waves
crests
troughs
are waves of electric and magnetic energy
frequency
the number of waves produced per second
amplitude
the distance from trough to crest
spectrum
gamma rays
passes through all materials excepr very thick or heavy solids
X-rays
pass through many solid materials
infrared radiation
causes warming if radiation is absorbed
visible light
triggers chimical reactions
ultraviolet radiation
tans or burns skin and can cause cancers
microwaves
induces matching oscillating electric currents in conductors
radio waves
sky waves
surface wave
space wave
Medical imaging
radiography
using X-rays
ultrasound image
using sound waves
thermography
for thermal imaging, heatres, cookers
computerised axial tomography
using X-rays
magnetic resonance imaging
using radio waves and magnetic field
positron emission tomography
using gamma rays
Trasmitting Telecommunications Tignals
digital
the signals are converted into a simple code
analogue
uses signal reproductions of sound or image
telephone networks
use a system of digital switches
cellular telephone
use radio signals
cables
coaxial cables
have two separate conductors
fibre optic cables
carry messages in the form of light
