Facts about photons
PHOTONS
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Smallest quantity of
electromagnetic
radiation
bundle of energy
(AKA quantum)
travels at 186,400
miles per second
x-ray and visible
light photons
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energy disturbances
no mass
have electric and
magnetic fields that
move in sine waves
ELECTROMAGNETIC
RADIATION

James Clerk Maxwell discovered both
light and x-rays have electric and
magnetic properties
TERMINOLOGY OF A SINE
WAVE
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AMPLITUDE: 1/2 RANGE FROM
CREST TO VALLEY
FREQUENCY: RISE AND FALL OF
SINE WAVE (HZ).
ONE HZ IS EQUAL TO ONE CYCLE
PER SECOND
WAVELENGTH: DISTANCE FROM
ONE VALLEY TO ANOTHER OR ONE
CREST TO ANOTHER
FACTS ABOUT “C”, “F” AND
LAMBDA
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C or V = velocity
C increases as F(FREQUENCY)
increases
As LAMBDA (WAVELENGTH)
increases, F decreases
V = F x Lambda
C = F X Lambda in electromagnetic
radiation
Match the Units of measurement
 Hz
 Energy
 Meter
 Frequency
 Volts
 Wavelength
MISCELLENOUS FACTS
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80 kVp= energies from 0-80 keV
x-rays are emitted from electron cloud
gamma rays emitted from nucleus
DEFINITIONS
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Reflection
Transmission
Absorption
Transparent
Translucent
Opaque

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Significant in
Radiology
Attenuation
Radioopaque
Radiolucent
PLANCK’S QUANTUM
THEORY
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Understanding of relationship between
energy and frequency
X-ray photons travel at speed of light
and exist with velocity or do not exist at
all
photon energy is proportional to photon
frequency
Planck’s constant
Application of Planck’s Constant
E(eV)=h(Planck’s constant or constant
of proportionality*)x f(photon frequency)