X-RAYS
These are electromagnetic radiations (waves) of very short wavelengths ranging from `0.1` to `100 -`. A surprising fact is, their discovery was accidental by the scientist Wilhelm K. Roentgen in the year 1895 in Germany.
So, when cathode X-rays (fact moving electrons) are braked by a material, their kinetic energy is converted into electromagnetic radiations. These are X- rays.
`text(Experimental Setup)`
A filament F heated electrically is forced to emit electrons (by thermionic emission). A metal target T (of high atomic weight and high melting point) maintained at a large positive potential ( > >20 keV - 30 keV) with respect to the anode (filament) draws the emitted electrons. The electrons, stopped by the target, release their kinetic energy in the form of X-rays
`text(Type of X- rays)`
`(a)` `text(Continuous X - ray)`
`(b)` `text(Characteristic X- ray)`
`text(Continuous X - ray) : `
This type (of X-rays) depends only on accelerating voltage. As per the electromagnetic theory, an accelerated charge will radiate electromagnetic waves when a fast moving electron is brought to rest (here electron gets decelerated) we get X-rays. X-rays produced this way are known as `text(bremsstrahlung)` (braking radiation)
The continuous X-rays `text((bremsstrahlung)` X-ray) produced at a given accelerating potential V vary in wavelength but none has a wavelength shorter than a certain value I min (also known as cut - off wavelength).
`text(Min. Wavelength at Max. energy of X-rays at Max. energy of Striking Electron)`
`(hc)/(lambda_(min)) = eV`
`lamda_(min) = (hc)/(eV) approx 12375/V -`{fig-b}
`text(Characteristic)` X-ray :
These are produced due to knocking out of electrons of target metal atom by energetic electron beam as it impinges and penetrates into target metal. When electron from K-shell is dislodged, the vacancy so created triggers electronic transition and electron from higher level jumps to fill up the created vacancy radiating difference of energy in the form of X-rays. X-rays produced due to K-shell electrons knock out form a series known as `text(K- series)` . Similarly, when electron from L shell is knocked out, the series so obtained is known as `text(L - series)` . The members of series are designated as a , b , g , d etc. as shown in figure{c,d}
So, when cathode X-rays (fact moving electrons) are braked by a material, their kinetic energy is converted into electromagnetic radiations. These are X- rays.
`text(Experimental Setup)`
A filament F heated electrically is forced to emit electrons (by thermionic emission). A metal target T (of high atomic weight and high melting point) maintained at a large positive potential ( > >20 keV - 30 keV) with respect to the anode (filament) draws the emitted electrons. The electrons, stopped by the target, release their kinetic energy in the form of X-rays
`text(Type of X- rays)`
`(a)` `text(Continuous X - ray)`
`(b)` `text(Characteristic X- ray)`
`text(Continuous X - ray) : `
This type (of X-rays) depends only on accelerating voltage. As per the electromagnetic theory, an accelerated charge will radiate electromagnetic waves when a fast moving electron is brought to rest (here electron gets decelerated) we get X-rays. X-rays produced this way are known as `text(bremsstrahlung)` (braking radiation)
The continuous X-rays `text((bremsstrahlung)` X-ray) produced at a given accelerating potential V vary in wavelength but none has a wavelength shorter than a certain value I min (also known as cut - off wavelength).
`text(Min. Wavelength at Max. energy of X-rays at Max. energy of Striking Electron)`
`(hc)/(lambda_(min)) = eV`
`lamda_(min) = (hc)/(eV) approx 12375/V -`{fig-b}
`text(Characteristic)` X-ray :
These are produced due to knocking out of electrons of target metal atom by energetic electron beam as it impinges and penetrates into target metal. When electron from K-shell is dislodged, the vacancy so created triggers electronic transition and electron from higher level jumps to fill up the created vacancy radiating difference of energy in the form of X-rays. X-rays produced due to K-shell electrons knock out form a series known as `text(K- series)` . Similarly, when electron from L shell is knocked out, the series so obtained is known as `text(L - series)` . The members of series are designated as a , b , g , d etc. as shown in figure{c,d}