X-rays are fundamentally electromagnetic radiations which produced when fast moving electrons strike with a metal anode in a discharge tube. When these striking electrons stop at once on collision with a metal anode the released energy is in the form of electromagnetic waves.
In a detailed procedure the electrons are first
produced in the discharge tube by heating the tungsten filament. These electrons
are then accelerated through high voltage which provides these electrons
sufficient energy to emit x-rays on striking the metal target. The wavelength
of the emitting x-rays solely depends upon the nature of metal selected as
target anode.
Henry G. J. Moseley worked a lot of experiments on
x-rays and used different metals as target anode ranging from Al to gold. He also
discovered x-rays spectrum and explain some fundamental concepts about x-rays
given as follows.
1.
The spectral lines obtained through x-rays
can be divided into two different groups depending upon the wavelength.
(i). K series
The
spectral lines of x-rays falling in K series possess shorter wavelength.
(ii). L series
The
spectral lines of x-rays in L series have longer wavelength.
2.
The
of produced x-rays is highly dependent upon the atomic number of target metal. If
the target metal is of higher atomic number, the wavelength of x-rays produced
will be shorter and vice versa.
3. Moseley’s law:
This law states that ‘The square root of frequency
of a spectral line in x-rays varies directly with the change in atomic number
of the target metal producing the x-rays spectrum”.
Where
Z
= atomic number of target metal
While
a & b are constants
Thus according to
equation 1 the frequency of the x-rays produced solely depends upon the atomic
number of the target metal.
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