X-rays are the invisible electromagnetic radiation having great energy and penetrating power. Their wavelength is smaller than that of visible light and their velocity matches with the speed of light. X-rays are used in medical diagnosis, industry and research. These rays were discovered by Prof. Wilhelm Conrad Roentgen, a German scientist in 1895. These rays are called X-rays because ‘X’ means unknown and these rays were not known earlier. They are also called ‘Roentgen Rays’ and for this discovery Prof. Roentgen was awarded the first Nobel Prize of Physics in 1901.
X-rays are very advantageous for mankind. They can pass through substances like flesh, paper, rubber, wood through which ordinary light and ultraviolet light cannot pass. X-ray pictures are used by doctors to study the inside of the body. They are employed to trace the dislocation and fractures of bones, to study the diseases of lungs, to find the presence of stones in kidneys and gall-bladder, to diagnose tumors, to study tooth decay and other conditions etc. X-rays are also used in research to create different genetic forms of plants and animals. Again, for very sensitive measurement and for detecting flaws in manufactured products x-rays are used.
The apparatus employed for making X-ray is called as ‘X-ray tube’. The X-ray tube consisting of hard glass is fitted with two electrodes, which are joined to high voltage power flow. The electrode connected to the negative terminal is called ‘cathode’ and the one joined to the positive terminal is called as ‘anode’. Low pressure is formed inside the tube by pumping out the air from it. So when high voltage is applied between the electrodes, electrons emerge from the cathode and strike the anode or the target. As a result the X-rays emerge out of the tube. Hence, when X-rays fall on the body parts to be studied, photograph is recorded in the photo film kept behind that part. In this film the part of bones appears grey and from the X-rays photographs, the portion affected by the disease or defects are located very easily.