Imaging 1 CH 4 59-67

am optical physicist describes visible light in terms of

wavelength

what happens when sunlight passes through a prism?

it becomes the color of the rainbow

refraction

refraction definition

when photons of visible light deviate in line of travel

what does the prism actually do when light shines through it?

separates and groups emerging light into colors because different wavelengths are refracted through different angles [

wavelength values of white light

400-700 nm

what is the wavelength of the color violet (roughly)

400 nm

what is the wavelength of the color red (roughly)

700 nm

what segment does visible light occupy of the electromagnetic spectrum?

smallest

visible light is the only

portion of the electromagnetic spectrum we can sense directly

how many types of invisible light does sunshine contain?

2

what are the types of invisible light of the sun?

infrared and ultraviolet

infrared light consists of photons with wavelengths

longer than those of visible light BUT shorter than those of microwaves

what does infrared light heat?

any substance it shines on

infrared light can be considered

radiant heat

where is UV located on the electromagnetic spectrum

in between visible light and ioninzing radiation

ultraviolet light is responsible for

molecular interactions that can result in sunburn

a radio or television engineer describes radiowaves in terms of their

frequency

communication broadcasts are identified by their

frequency of transmission RF transmissions

RF energy and wavelength

low

long

ham radio broadcasting wavelengths

10 or 30 m bands

standard AM radiobroadcasts wavelength

100 m

television and fm broadcasting both have _____ wavelengths

shorter

RF and microwave emissions . . .

overlap considerably

what is microwave radiation?

very short wavelength radiofrequency

microwave frequencies are always higher than ____ and lower than

broadcast RF

infrared

list some microwave uses

cell phone communication

highway speeed monitoring

medical diathermy

hot dog prep

ionizing electromagnetic energy is characterized by what

energy contained in a photon

an x ray photon contains ___ energy than a visible light photon or RF photon

MORE

the frequency of x-radiation is _____ and the wavelength is ______ than other types of electromagnetic energy

much higher

much shorter

in the early days what was said about gamma rays?

they had higher energy

what do linear accelerators do in terms of energy

make x rays with higher energy than gamma ray emissions

only difference between x ray and gamma ray

ORIGIN

x rays are emitted from

electron cloud of atom that has been artificially stimulated

gamma rays are emitted from

inside nucleus of radioactive atom

x rays are produced in

diagnostic imaging

gamma rays are emitted

spontaneously from radioactive material

would you be able to tell an x ray and gamma ray apart of equal energy

NO

difference between beta particles and electrons

ORIGIN

beta particles origin

inside the nucleus

beta electrons origin

outside the nucleus

visible light is identified by

wavelength

RF is identified by

frequency

x rays are identified by

energy

3 regions electromagnetic energy important to x ray are

x ray

visible light

rf

the x ray region is

fundamental to produce a high quality x ray

why is the visible light region important?

viewing conditions of x ray or fluoro image are CRITICAL to diagnosis

importance of RF region

MRI

a photon of x-radiation and a photon of visible light are

the same EXCEPT xradiation has a higher frequency and shorter wavelength

visible light photons behave like

waves

x ray photons behave like

particles

wave-particle duality of electromagnetic energy

wave and particle behavior of visible light and x ray photons

photons interact with matter most easily when the matter is

the same size as the photon wavelength

radio and tv waves interact with

antennas (metal rods or wires)

radio and tv wavelengths are measured in

centimeters

microwave wavelengths are measured in

nanometers

microwaves interact most easily with objects that are

the same size

hot dogs and hamburgers

visible light interacts with

living cells

• rods and cones of eye

UV light interacts with

molecules

x rays interact with

electrons and atoms

all radiation with a wavelength longer than those of x radiation interact primariyly as

wave phenomenon

x rays behave as though they are

particles

visible light spectrum extends forom (think colors and wavelengths)

short wavelength violet radiation through green and yellow to long wavelength red radiation

how can UV light and infrared light be detected

photographic emulsion

how does visible light interact with matter compared to x rays

very different

what happens when a photon of light strikes an object?

objects molecules are set in vibration

reflection - interaction of matter example

orbital electrons are of molecules that are excited to high of an energy level are remitted as another photon of light

the atomic and molecular structures of any object determine

which wavelengths of light are reflected

why is a leaf green in the sun?

all visible light photons are absorbed by the leaf

only photons with green wavelength are reflected

what phenonmena of light are explained by the wave model of electromagnetic energy?

reflection

absorption

transmission

visible light behaves like a

wave

the shorter the photon wavelength the

higher the photon energy

electromagnetic energy attenuation is the

reduction in intensity that results from scattering and absorption

reflection example

mirror

when light waves are absorbed the energy deposited in the absorber

reappears as heat

a black asphalt road reflects _________ but absorbs _______

very little light

a considerable amount - becomes hot

3 degrees of interaction between light and absorbing material

transparency

translucency

opacity

example of transparent object

window glass

transparent definition

allows light to be transmitted almost unaltered

why can you see through glass

surface is smooth

molecular structure is tight and orderly

when the surface of glass is roughened with sandpaper light is

still transmitted through glass but greatly scattered and reduced in intensity = becomes blurred

translucent example

frosted glass

when glass is painted black