Download EM Spectrum notes - Biloxi Public Schools

Term 1---EM Spectrum Notes
1
electromagnetic  transfers electrical and magnetic
wave (EM)
energy
 vibrating electric and magnetic
fields that move through space at the
speed of light
 light and sound combinations-sometimes one sees the light before
hearing the sound because light
travels faster than sound
 speed of all EM waves is the same
 planes, rockets, fireworks, explosion,
thunder/lightning
 waves of the spectrum
 The speed of light changes speed as it enters
a different medium. The light will refract or
bend.
 EM waves can travel not only through air
and solid materials, but also through the
vacuum of space.
 vacuum---a space entirely devoid of matter
electromagnetic  transferred through space by
radiation
electromagnetic waves
 radiation is energy that travels and
spreads out as it goes
 emitted by stars and space objects
 Mnemonic device: Rabbits mate in
very unusual expensive gardens.
 Radio waves
 Micro-waves
 Infra-red radiation
 visible light
 Ultra-violet radiation
 X-rays
 Gamma rays
electromagnetic  complete range of electromagnetic
spectrum
waves placed in order of increasing
(EM spectrum)
frequency
 EM spectrum has benefited the
study of astronomy
 Hotter, more energetic objects and
events create higher energy
radiation than cool objects.
 Only extremely hot objects or
particles moving at very high
velocities can create high-energy
radiation like X-rays and gammarays.
Term 1---EM Spectrum Notes
Type
Information
radio waves
 longest
wavelengths
 lowest energy
microwaves
Infrared (IR)
light
Visible light
ROYGBIV
Ultraviolet
(UV) light
X-rays
Gamma rays
2
Effects on Living Things/Uses by People
 transmits radio and television signals
 cell phones and radar
 can travel long distances
 TV and FM radio use shorter wavelengths than AM radio
 GPS (global positioning system)
 Shorter
 cook in microwave ovens
wavelengths and  weather Doppler effect radar
higher frequency  police radar
than radio waves  used by astronomers to learn about the structure of nearby
galaxies and our own Milky Way
 fairly long (about  Used by some insects (IR-sensitive beetles) and snakes (pythons,
the length of a
pit vipers)
fingernail), low Felt as heat by humans
frequency waves  Night vision goggles use infrared sensors
 heat from the sun  Infrared cameras used by firefighters to locate fire victims
travels to Earth in  heat lamps---used to keep food warm and to heat bathrooms
this form
quickly
 thermograms are  infrared heat lamps can be used by pet owners to help their
thermal images
reptiles maintain internal (core) body heat
using IR
 satellites in space use infrared cameras to study the growth of
plants and motions of clouds
 in space, IR light maps the dust between stars
 only part humans  Nearly 90% of the light energy used by plants for photosynthesis
see---red, orange,
comes from red light
yellow, green,
 Light that comes from a lamp in your house
blue, indigo,
***red shift means longer wavelengths (moving away) and blue
violet
shift means shorter wavelengths (moving closer)***
(**Big Bang Theory---universe continues to expand---red shift)
 can make certain  used by bees and some other insects to see
minerals glow
 Prolonged exposure can damage cells (ozone layer---O3)
 not visible to
 Causes skin to make vitamin D
humans
 Can burn skin or lead to skin cancer in humans and some other
animals
 Photosynthesis
 Greenhouse gases (CO2, CH4)—short wave UV radiation is
allowed to enter the atmosphere but long wave infrared radiation
is trapped by the gases which causes the Earth to warm
(greenhouse effect)
 May kill some bacteria in sewage treatment plants
****ways astronomers identify the hottest stars***
 can travel
 Repeated exposure can damage cells
through soft
 Used for medical imaging (bones, teeth)
tissue, such as
 Used in security checks to find hidden objects
skin and muscle,  by engineers to check for cracks in steel or concrete
but not through
 used to check the quality of joints in oil and gas pipelines
hard bone
 Hot gases in the Universe also emit X-rays
 highest
 Very damaging to cells
energy/frequency  Used to sterilize medical equipment by killing any germs
 produced by stars  Nuclear energy
 Cancer treatment
Term 1---EM Spectrum Notes
apparent
 measure of the amount of a
magnitude
star’s light received on Earth
 how it appears
absolute
magnitude

measure of the amount of the
light given off by a star
Big Bang
Theory

was incredibly hot and dense
and an expansion quickly
happened
universe cooled over time
forming stars, planets
13.7 billion years ago
The universe continues to
expand by measuring the
wavelengths of radiation
from galaxies.
supported by red shift
objects moving away from
Earth
longer wavelength
Doppler effect
spectral lines shift towards
red



red shift





3
Term 1---EM Spectrum Notes
blue shift
 objects moving towards Earth
 shorter wavelength
 spectral lines shift towards
blue or violet
stars
Milky
Way
Galaxy









light-year

Telescope
Hierarchical Structure of the Universe

clusters
galaxies 
galactic clusters  universe
our solar system is a part of it
stars you can see at night are
part of the Milky Way
our sun is only one of the
many stars in our galaxy
spiral with roughly 100
billion other stars
spiral arms and a bright
central part
sun is halfway to the edge of
galaxy along Orion spiral
arm
100,000 light-years across
Black hole at the center
cannot see the spiral shape of
the Milky Way Galaxy from
Earth because we are located
within one of its spiral arms
how far light can travel in
one year
Type of
Radiation
Visible light
Source of
Radiation
Stars, planets,
moons
radio
Radio waves
ultraviolet
Ultraviolet
infrared
Infrared
Microwave
observatories
Microwave
Galactic
centers, stars,
black holes
Distant stars, 
clouds of dust 
and gas
Stars, galaxies 


Dark matter, 
energy
Optical
(reflecting and
refracting)
4
---approximately 6 trillion miles
Some Uses
 to gather and focus light
 To study the size, composition, and movement of stars
and galaxies
 They make distant objects appear closer and brighter.
 To find black holes and map galactic centers
 Some have been used to monitor radio signals given off
by earthquakes
To map sources and analyze their composition
Stars and other "hot" objects in space emit UV radiation
(determines the hottest stars in our galaxy)
To study planets around other stars
in space, IR light maps the dust between stars
discover distant galaxies
locate dark matter in galaxies
****some telescopes must be placed outside of Earth’s atmosphere in order to gather data due to
interference with the atmosphere