What is the EM Spectrum
0 We learned in section 1 that all EM waves travel at the
same speed in a vacuum (empty space), but their
wavelengths and frequencies are different.
0 Because of these differences each type of wave have
different properties.
0 There is an inverse (opposite) relationship that exist
between WL and F.
0 As the length of a wave decreases its frequency goes
increases.
0 The EMS is placed in order from lowest frequency
(Radio waves) to the highest frequency (Gamma Rays)
Radio Waves
0 Radio waves: are EM waves with the longest
wavelength and lowest frequency. These waves are
used to broadcast signals for radio and television.
0 A Radio will absorb the Radio wave and transform the
wave into an electrical signal
Microwaves
0 Microwaves: are Radio waves with the shortest WL
and highest frequencies.
0 Microwaves are used to heat food, cell phone
communication, and radar
0 Radar (radio detection and ranging), this system uses
reflected radio waves to detect objects and measure
their distance and speed.
Infra[red]
0 Infrared waves are detected through heat given off by
an object.
0 These waves are used by fast food industries to keep
food warm
0 Thermogram is an image that shows regions of
different temperatures in different colors. The
blue/purple colors would be the coolest and the
yellow/orange/red areas are the warmest
Visible Light
0 These are the waves that you can see
0 The VL waves with the longest wavelength appears
Red while the VL wave with the shortest wavelength
appears Violet.
0 The colors in order from longest to shortest
wavelengths are R O Y G B (I) V
0 These colors are seen when White light waves from
the sun are refracted and the light separates into
those colors.
Ultraviolet Rays
0 This wave carries enough energy to damage or kill
living cells. UV lamps are often used by hospitals to
kill bacteria on hospital equipment.
0 Small doses are useful. They can cause your skin cells
to produce Vitamin D which is needed for healthy
bones and teeth.
0 To much exposure can cause skin cancer and damage
your eyes.
0 To prevent wear sunblock and sunglasses
X-Rays
0 These rays carry enough energy to penetrate most
matter except dense matter like Bone and Teeth, and
the lead vest the doctor will lay across you when
taking X-rays
0 Too much can cause cancer
0 X-rays also have industry uses (the Hubble telescope
uses X-rays to detect black holes and far off galaxies)
Gamma Rays
0 These rays have the shortest wavelength and highest
frequency.
0 These rays can penetrate any substance because of
there high energy level
0 Hospitals use Gamma rays to kill cancer cells inside
the body
0 Our atmosphere blocks out gamma rays