The Inverse Square Law can be applied to distances greater than _________ times the longest dimension of the source
The inverse square law can be applied to distances greater than SEVEN times the longest dimension of the source.
States that the intensity of radiation at a location is inversely proportional to the square of its distance from the source.
The Inverse Square Law
A discrete bundle of energy
the x-ray photon
Photon energy is directly proportional to
photon frequency
Photon energy is ____________ proportional to photon wavelength
Photon energy is INVERSELY proportional to photon wavelength.
X-rays exist:
at the speed of light or not at all
E=hf
Planck's Quantum Equation
The longer the wavelength, the _____________ the energy of each photon.
Lower
(longer=lower)
The law of conservation of mass & energy states:
Energy & Matter can neither be destroyed or created
The properties of elctromagnetic radiation include:
(4)
frequency
wavelength
velocity
amplitude
Electromagnetic energy exists over a wide range called:
an energy continuum
A continuum is an uninterrupted (continuous) ordered sequence.
An atom of light
Photon
The smallest quantity of any type of electromagnetic energy
photon
A photon may be pictured as a small bundle of energy, sometimes called a
Quantum
A quantum of electromagnetic energy
an x-ray photon
Energy disturbances that move through space at the speed of light
photon
Mass of a photon
Photons have NO MASS
but they do have electric and magnetic fields
Speed of light
3x108 m/s
The speed of light (c)
The velocity of electromagnetic radiation
3 x 108 m/s
Variations of amplitude over time
Sine wave
One-half the range from crest to valley over which the sine wave varies
Amplitude
The number of wavelengths that pass a point of observation per second
Frequency (f)
measured in Hertz (Hz)
The rate of rise and fall
Frequency (f)
What is frequency measured in?
Hertz (Hz)
One hertz is equal to one cylce per second
ie. 20 cycles in 10 sec is 2 Hz
The distance from one crest to another, one valley to another or from any point on the sine wave to the next corresponding point
Wavelength
What are the 3 parameters needed to describe electromagnetic energy?
Velocity (v- measured in m/s)
Frequency (f- measured in Hz)
Wavelength
At a given velocity _______________ & ______________ are inversely proportional
wavelength & frequency
For electromagnetic energy, frequency and ____________ are inversely proportional
wavelength
The deviation of course that occurs when photons of visible light traveling in straight lines pass from one transparent medium to another
Refraction
________ light consists of photons with wavelengths longer than visible light but shorter than microwaves
Infrared light
___________ light is between visible light & ionizing radiation on the spectrum
Ultraviolet light
An x-ray photon contains ___________ energy than a visible light photon or an RF photon
considerably more
The frequency of x-radiation is much _________ and the wavelength is much _________ than for other types of electromagnetic energy
Higher (frequency)
Shorter (wavelength)
Where are x-rays produced?
Outside of the nucleus of excited atoms; emitted from the electron cloud
Where are gamma rays produced?
Inside the nucleus of the atom
A photon of x-radiation & a photon of visible light are fundamentally the same except that x-radiation has ________ frequency & hence a _________ wavelength
Higher (frequncy)
Shorter (wavelength)
X-rays are identified by
Energy
Visible light tends to behave more like
Waves
X-ray photons tend to behave more like
Particles
The reduction in intesnsity that results from scattering and absorption
Attenuation
Transfer of energy from an electromagnetic field to matter.
Removal of x-rays from a beam via the photoelectric effect.
Absorption
Return or re-entry of an x-ray
Reflection
Passage of an x-ray beam through an anatomical part with no interaction with anatomical structures