The Electromagnetic spectrum
Radio waves (real)
Microwaves (monkeys)
no danger. we are constantly exposed to them
Transmitting signals
not very harmful apart from 2.4GHz
transmitting signal
Heating things
Infra-red (in)
can't use them but can feel them from ovens etc.
Energy is absorbed- Heat(thermal)
Fibroptics- signal
Visible (Vietnam)
Allow us to see everything
Non-harmful
Ultra violet (understand)
more energy efficient
used for dental treatment
security pens
it comes from the sun
can give you a suntan
too much can lead to cancer
X-ray (excellent)
They pass through soft tissues in the body
used in radiology to treat cancer
over exposure however can lead to cancer
also in security scanners
Gamma rays (gorillas)
they transfer the most energy of all the waves.
Can be harmful to living cells
used to kill cancerous cells
the radiation dose can also lead to cancer
Radio waves have the longest frequency
Gamma rays have the shortestt frequency
The sun emits EM waves of all frequencies however some are more capable of penetrating our atmosphere than others
radio, visible light, UV can reach the earth
low frequency, long wavelength
Visible light
Violet has the highest frequency around 10 to the power of 16 Hz
Red has the longest wavelength of 700nm
Infrared
thermal imaging cameras can 'see' infrared
different objects at different temps give out slightly different frequencies of infrared
different colours correspond to different temperatures.
heat radiating travels in a straight line and at the speed of light much like most radiation
Bodies that give out heat radiation are called emitters
Dull dark surfaces are the best type for emitting radiation