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What is wavelength?
Distance between successive peaks in a wave.
Wavelength of radio waves?
In the range of 100m.
Wavelength of visible light?
300nm to 800nm.
Wavelength of x-rays?
0.01nm to 0.05nm.
Describe x-ray wave form?
Short wavelength high frequency wave.
Relationship of energy to wavelength and frequency?
Energy is directly proportional to frequency and inversely proportional to wavelength. Short wavelenght with high frequency implies a high energy wave.
X-rays are ionizing radiations. What are other types of ionizing radiation?
Gamma radiation, Higher energy UV radiation.
X-rays have ___ mass and charge.
no
X-ray vacuum glass tube have a ___ filament and ___ target.
cathode, anode
Cosmic are ___ detrimental than x-rays.
more
Filament and target are both made of ___.
tungsten
Focusing cup is made of ___.
molybdenum
How are x-rays produces?
Electrons are emitted from filament, electrons travel at very high speed, electrons collide with target converting KE to EM radiation.
Electrons are emitted from tungsten filament by ___.
thermionic emission
Potential difference used in x-ray tube is measured in ___
kilovolts
Tube current used to heat filament and produce electrons is measured in ___. It is called ___.
milliamperes, tube current
___% of electron interactions at target produce heat, ___% produce x-rays.
99, 1
Increasing mA does what?
Increases number of electrons emitted - image becomes darker.
Increasing kV does what?
Increases energy of electrons - image contrast increases.
What is exposure time?
Length of time the electrons move across the tube.
Exposure time is measured in …?
seconds or impulses
An impulse is equal to …?
1/60 of a second.
Two mechanisms through which x-rays are produced?
Bremsstrahlung radiation.Characteristic radiation.
Binding energy is highest for electrons in the ___.
K shell (since they are closest to nucleus)
Binding energies are greater in ___.
elements with more protons - like tungsten
Describe Bremsstrahlung radiation mechanism?
Electrons approach the positive charges in the nucleus. They are either slung around or they hit the nucleus. When the electron slows down KE is converted to EM radiation, including x-rays.
Percentage of x-rays produced by Bremsstrahlung mechanism?
85 - 90%
X-rays produced by Bremsstrahlung mechanism are ___.
polyenergetic (have multiple energy levels - since electrons slow down at various rates)
Describe Characteristic radiation mechanism?
Electrons strike a K shell electron and ionize it. Vacancy in K shell is filled by electron from L shell. The difference in binding energies between the two shells is emitted as x-rays.
Why is it called characteristic radiation?
It is characteristic of the particular element since binding energies differ in different elements.
Percentage of x-rays produced by Characteristic mechanism?
10 - 15%
X-rays produced by Characteristic mechanism are ___.
monoenergetic (have only one energy level)
Bremsstrahlung mechanism is associated with ___.
number of photos emitted
Characteristic mechanism is associated with ___.
energy level of x-rays
x of y cards