Quality of x-rays 


The quality of x-rays may be defined as their penetrating power that is the ability of an x-rays beam to pass through a given part of the body. It is determine by the energy of the x-rays. Thus the ability of x-rays depended upon their energy.




Factors determine quality of x-rays



Since quality depend upon the energy of the electrons emitted from the filament is incident on the target as they get accelerated towards the target. Let v is the potential difference between the filament and the target. And the kinetic energy acquired by electrons is ½ mv2 =ev where e, m and v are the charge, mass and velocity of the electron. Since Kinetic energy depends upon V, so by increasing V, Kinetic energy can be increased and vice versa.





Hard and Soft x-rays



X-rays may be classified on the basis of their quality as hard and soft.



1. X-rays of high penetrating power are called hard X-rays. The hard x-rays are high energy photons with high frequency or short wavelength. These are produced by applying high voltage between the cathode and the anode, and using target of high atomic number. 





2. X-rays of low penetrating power are called soft x-rays. The soft x-rays are low energy photons with low frequency or high wavelength. They may be produce by applying low voltage between the cathode and anode, and using of low atomic number 





So hence X-rays of wavelength <<1A◦ are called hard x-rays and x-rays of wavelength >>1A◦ are called soft x-rays. 





Intensity of X-Rays 



The intensity of the x-rays depends upon the no. of electrons falling on the target which is depend upon the current into the filament F. If filament current increases more electrons are liberated per second which increases the intensity of x-rays. 





It may be noted that the change of the filament current does not affect the quality of x-rays.





Intensity at a given wavelength 




Intensity of x-rays emitted at a given wavelength λ is defined as- consider a small wavelength range dλ from λ-dλ/2 to λ+dλ/2 about a wavelength λ. Let DE is the amount of energy emitted per second in this small range dλ of wavelength. Then the intensity at the given wavelength is defined as-


I(λ)=dE/dλ