X-RAY

X-RAY:Electromagnetic radiation having wavelength ranged from 0.1 arm strong to 100 arm strong are called x-ray.It consists of an evacuated round tube containing a tungsten filament at one end connected with 9v (10w tension) battery . As electric current flows along filament, it gets heated and then electron evaporates from its surface.Electrons beam is collocated by the help slit placed near it. These electrons are accelerated by keeping a target made of high atomic weight element at positive potential with respect to filament,when accelerated(i.e energetic) electrons strike tungsten target, few electrons staying at the lower energy level in tungsten atom are knocked out and then vacancies created are filled up with the transition of electron from higher energy level giving the emission of electromagnetic radiation.These emissions are x-rays.Maximum energy of a photon of x-rays produced is equal to the maximum energy of striking electron.
i.e 1/2mv^2 = ev =hf maximum
therefore f maximum= ev/h
Hence,the frequency of x-rays emitted depend on the potential difference applied between filament and target used . The number of increased by increasing the filament current.
Only a fraction of electron beam energy is used up in the production of x-rays and the large part of electron beam energy is converted in producing heated Target. A water cooling arrangement is provided to exchange heat from target.
PROPERTIES OF X-RAYS:

1. They are electromagnetic Waves with wavelength from 0.1 to 100 arm strong.
2. They travel with 3*10^8m/s velocity in vac cum in straight line.
3. They are uncharged rays and so not deflected by electric and magnetic field.
4. They can ionise the gas through soft substance like paper,flesh,wood etc but cannot pass through hard substance like steel sheet and bone.
5. They can affect photographic plate i.e. they have reducing action on silver halide compound.
6. They show fluoresce effect on the substance like zinc sulphide and barium platino cynide.
7. They are diffracted when pass through thin sheet of crystal.

USES OF X-RAYS
They are used in various fields as given below:

1. Medical use : Physitotheraphy (a) They are used to cure malignant skin disease by exposing skin to x-ray beam.(b)Surgery: They are used to detect the disorders in certain internal organ, presence of hard substance in internal organ and fracture of bone.
2. Industry and engineering: They are used to detect the presence of air bubbles and cracks in valuable finished product in factory.
3. Investigation: They are used to detect the presence of arms explosive and opium inside large packets.
4. Scientific research : They are used to know the crystal structure of substance and to measure the inter atomic distance in crystal.

X-RAY DIFFRACTION
IN 1912A.D van lau found that x-rays are diffracted when a narrow beam of x-rays incident on thin sheet of zinc sulphide. The spot produced on photographic plate after emerging from thin sheet of zns was arranged in regular way. It was concluded that atoms must be arranged in regular pattern in zns sheet and diffraction occurs because the space between two atoms act as slit having dimension in the range of wave length of x-rays used.