Bushong Ch 4
Name some uses of microwaves:
*cell phone communication *highway speed monitoring *medical diathermy *hot dog preparation
The important properties of the sine wave model of electromagnetic energy:
*frequency (f) and *wavelength (represented by the Greek letter lambda)
List the 4 properties of electromagnetic energy:
*frequency *wavelength *velocity *amplitude
List the 4 properties of photons:
*frequency *wavelength *velocity *amplitude
sunlight contains these 2 types of invisible light:
*infrared *ultraviolet
3 degrees of interaction between light and an absorbing material:
*transparency (transmission) *translucency (attenuation) *opacity (absorption)
The 3 wave parameters needed to describe electromagnetic energy:
*velocity *frequency *wavelength
3 regions of the electromagnetic spectrum most important to radiologic science:
*visible light *x-radiation *radiofrequency
Name 2 mathematical formulas that describe how electromagnetic energy behaves
*wave equation *inverse square law
List 3 examples of electromagnetic energy:
*x-rays *visible light *radiofrequencies
the x-ray energy ranges
10 keV to 50 MeV
the associated wavelength for x-ray energy
10^-10 to 10^-14 m
the range of x-ray photon frequency
10^18 to 10^22 Hz
the speed of light as represented by the SI system of units
3 x 10^8 m/s
the velocity of all electromagnetic radiation
3 x 10^8 m/s
the numeric value for Planck's constant
4.15 x 10^-15
Planck's Quantum Equation
E = hf (where E is the photon energy, "h" is Planck's constant, and "f" is the photon frequency in hertz)
Einstein's Relativity Equation
E = mc^2 (E is the energy measured in joules, "m" is the mass measured in kilograms, and "c" is the velocity of light measured in meters per second)
In the late 19th century, he showed that visible light has both electric and magnetic properties
James Clerk Maxwell
states that energy can be neither created or destroyed
Law of Conservation of Energy
states that matter can be neither created or destroyed
Law of Conservation of Matter
a German physicist whose mathematical and physical theories synthesized our understanding of electromagnetic radiation into a uniform model
Max Planck
he received the Nobel Prize in 1918
Max Planck
the constant of proportionality is know as this:
Planck's constant
covers a considerable portion of the electromagnetic spectrum and has relatively low energy and relatively long wavelength
RF (radio frequency)
How is the energy of a photon and its frequency related?
The energy of a photon is directly proportional to its frequency.
How is the energy of a photon related to its frequency?
The energy of a photon is directly proportional to its frequency.
At what distance from the source can the inverse square law be applied?
The inverse square law can be applied to distances greater than seven times the longest dimension of the source.
principle that states that both wave and particle concepts must be retained, because wave-like properties are exhibited in some experiments and particle-like properties are exhibited in others
Wave-particle duality
One of the substantive statements of Planck's Quantum Theory
X-rays are created with the speed of light (c), and they exist with velocity (c) or they do not exist at all.
visible light behaves like
a wave
one-half the range from crest to valley over which the sine wave varies
amplitude
a quantum of electromagnetic energy that travels through space at the speed of light
an x-ray photon
contains considerably more energy than a visible light photon or an RF photon
an x-ray photon
The Electromagnetic Wave Equation:
c = frequency x wavelength
an uninterrupted (continuous) ordered sequence
continuum
this imaging modality is not a part of the electromagnetic spectrum
diagnostic ultrasound
a field or state of energy that is always present around us and exists over a wide range called an energy continuum
electromagnetic energy
the reduction in intensity that results from scattering and absorption
electromagnetic energy attenuation
this includes the entire range of electromagnetic energy
electromagnetic spectrum
x-rays are identified by:
energy
physicists use this term to describe the interactions among different energies, forces, or masses that can otherwise be described only mathematically
field
RF is identified by:
frequency
the number of wavelengths that pass a point of observation per second
frequency
these come from inside the nucleus of a radioactive atom
gamma rays
consists of photons with wavelengths longer than those of visible light but shorter than those of microwaves
infrared light
How is electromagnetic energy (radiation) intensity related to the square of the distance from the source?
inversely
at a given velocity, wavelength and frequency are:
inversely proportional
for electromagnetic energy, frequency and wavelength are:
inversely proportional
today, these make it possible to produce x-rays of considerably higher energies than gamma ray emissions
linear accelerators
these frequencies vary according to use but are always higher than broadcast RF and lower than infrared
microwave frequencies
very-short-wavelength RF
microwave radiation
an example of converting matter into energy
nuclear fission
the basis for generating electricity
nuclear fission
an example of converting energy into mass
pair production
x-rays behave as though they are
particles
the smallest quantity of any type of electromagnetic energy
photon
How is the energy of a photon related to its wavelength?
photon energy is inversely proportional to photon wavelength
a term that means "a small bundle of energy"
quantum
structures that transmit x-rays are called this:
radiolucent
structures that absorb x-rays are called this:
radiopaque
return or reentry of an x-ray
reflection
the deviation in the course of visible light when they pass from one transparent medium to another
refraction
variations of amplitude over time
sine waves
this term means "simple motion; a sine wave"
sinusoidal
the first ancient people to describe photons
the ancient Greeks
this governs the interaction of electrostatic charges, the magnetic field, and the interaction of magnetic poles
the electric field
unit of energy used to describe x-rays
the electron volt (eV)
this governs the interaction of different masses
the gravitational field
the unit of frequency that is used to describe radio waves
the hertz
describes the relationship between radiation intensity and distance from the radiation source
the inverse square law
Planck's constant is symbolized by
the letter "h"
this extremely small segment of the electromagnetic energy continuum is the only one that is naturally apparent to us
the visible light segment
the only difference between x-rays and gamma rays
their origin
the wavelength differences between a photon of x-radiation and a photon of visible light result in this difference between them
these differences result in differences in the way these photons interact with matter
What is the only way the photons of various portions of the electromagnetic spectrum differ?
they differ only in frequency and wavelength
located in the electromagnetic spectrum between visible light and ionizing radiation
ultraviolet light
The Wave Equation:
v = frequency x wavelength
occupies the smallest segment of the electromagnetic spectrum
visible light
the only portion of the electromagnetic spectrum we can sense directly
visible light
the distance from one crest to another, from one valley to another, or from any point on the sine wave to the next corresponding point
wavelength
visible light is identified by:
wavelength
When do photons interact with matter most easily?
when the matter is approximately the same size as the photon wavelength
these are emitted from the electron cloud of an atom that has been stimulated artificially
x-rays