The function of the step-up transformer in x-ray equipment is to:
a- Change AC voltage to DC.
b- Produce high voltage.
c- Increase milliamperes to amperes.
d- Reduce the power loss in the x-ray tube.
The discovery of X-rays is based on the 1869 discovery of cathode rays by Hittorf: physicists all over the world are looking into this invention without finding any practical application. In 1895, Röntgen decided to plunge a Crookes tube into an opaque box. He then realizes that the radiation passes through the material, and that the metallic elements are visible in negative. He deduces that the rays are invisible and that they are emitted in the direction of the electrons of this tube. Not finding an appropriate name, he calls them "X-rays" because of their unknown nature.
A first shot is made on the hand of Anna Bertha Röntgen December 22, 1895: after a pose of twenty minutes, the cliché clearly displays the ring on his finger. This is the first X-ray. Thanks to this discovery, Röntgen gets the first Nobel Prize in Physics.
Using X-rays:
X-rays can be produced in two ways: by producing electronic transitions on the inner layers, close to the nucleus: this is the principle of X-ray fluorescence spectrometry. They can also be produced by a braking of the electrons within an X-ray tube, on a metallic target: the radiation is called Bremsstrahlung.
Today, they are massively used in the field of medicine, security, especially at airports, but also, more recently, in the accurate imaging of fossils: they allow to cut (or slices) virtual without touching their structure. In space, we have individualized many sources of X-rays. The main sources of X-rays are supernovae, pulsars and quasars.
properties:
The interaction of the X-rays and the matter is conditioned by the values of their wavelengths and photon energy in relation, on the one hand, to the dimensions of the atoms and, on the other hand, to the energies of the bonding of atomic electrons.
Absorption of X-rays in matter:
The absorption of X-rays in the material results in the reduction of the intensity of the beam passing through a screen. The photons that disappeared from the transmitted beam or were deflected by diffusion or else were transformed by shock on the atoms, thus really absorbed by the material by photoelectric effect.
X-ray absorption is an atomic phenomenon: for a compound, it is simply the sum of the absorptions of the constituent elements; it does not depend on their modes of connection. Thus, the lead of the crystal (lead glass) produces the same absorption as a lead sheet of metal containing the same amount of lead as the glass per unit area.
The absorption of any substance is therefore easily calculated from the tables giving the coefficients for the elements as a function of the wavelength. In general, the absorption coefficient increases with the atomic number (approximately like Z3) and with the wavelength.
The hard, short-wavelength rays can traverse considerable thicknesses of matter without being completely extinguished, and it is this property, considered extraordinary when one knew only the light, which first drew attention to X-rays (discovery of Röntgen, 1895). The table gives the thicknesses of carbon, iron and lead screens, which reduce the intensity to 1/10 of the value of the incident intensity.
a- Change AC voltage to DC.
b- Produce high voltage.
c- Increase milliamperes to amperes.
d- Reduce the power loss in the x-ray tube.
The discovery of X-rays is based on the 1869 discovery of cathode rays by Hittorf: physicists all over the world are looking into this invention without finding any practical application. In 1895, Röntgen decided to plunge a Crookes tube into an opaque box. He then realizes that the radiation passes through the material, and that the metallic elements are visible in negative. He deduces that the rays are invisible and that they are emitted in the direction of the electrons of this tube. Not finding an appropriate name, he calls them "X-rays" because of their unknown nature.
A first shot is made on the hand of Anna Bertha Röntgen December 22, 1895: after a pose of twenty minutes, the cliché clearly displays the ring on his finger. This is the first X-ray. Thanks to this discovery, Röntgen gets the first Nobel Prize in Physics.
Using X-rays:
X-rays can be produced in two ways: by producing electronic transitions on the inner layers, close to the nucleus: this is the principle of X-ray fluorescence spectrometry. They can also be produced by a braking of the electrons within an X-ray tube, on a metallic target: the radiation is called Bremsstrahlung.
Today, they are massively used in the field of medicine, security, especially at airports, but also, more recently, in the accurate imaging of fossils: they allow to cut (or slices) virtual without touching their structure. In space, we have individualized many sources of X-rays. The main sources of X-rays are supernovae, pulsars and quasars.
properties:
The interaction of the X-rays and the matter is conditioned by the values of their wavelengths and photon energy in relation, on the one hand, to the dimensions of the atoms and, on the other hand, to the energies of the bonding of atomic electrons.
Absorption of X-rays in matter:
The absorption of X-rays in the material results in the reduction of the intensity of the beam passing through a screen. The photons that disappeared from the transmitted beam or were deflected by diffusion or else were transformed by shock on the atoms, thus really absorbed by the material by photoelectric effect.
X-ray absorption is an atomic phenomenon: for a compound, it is simply the sum of the absorptions of the constituent elements; it does not depend on their modes of connection. Thus, the lead of the crystal (lead glass) produces the same absorption as a lead sheet of metal containing the same amount of lead as the glass per unit area.
The absorption of any substance is therefore easily calculated from the tables giving the coefficients for the elements as a function of the wavelength. In general, the absorption coefficient increases with the atomic number (approximately like Z3) and with the wavelength.
The hard, short-wavelength rays can traverse considerable thicknesses of matter without being completely extinguished, and it is this property, considered extraordinary when one knew only the light, which first drew attention to X-rays (discovery of Röntgen, 1895). The table gives the thicknesses of carbon, iron and lead screens, which reduce the intensity to 1/10 of the value of the incident intensity.
