X- ray Production

X- rays

Production of X – rays :-

When fast moving electrons strike on a very hard target of high atomic number e.g. platinum, tungsten, molybdenum etc. X – rays are produced.

                Dr. William Collidge designed a tube for the production of X – rays. This tube is known as Collidge tube or modern X-ray tube.

Construction:-

Cathode consists of tungsten filament (F) heated by low tension battery which is placed in a molybdenum cup which helps to make focus on the target. When the electrons are emitted from the cathode they accelerated and strike on the target T such as platinum, molybdenum etc. . The target is held at an angle 45⁰ with horizontal. The target is held by copper pipe through which water is circulated. The target is connected to +ve terminal and cathode to negative terminal.

Working :-

When the current is passed through the cathode, the electrons are emitted these electrons are accelerated by applying p.d. across them by high tension battery. Electrons are accelerated and strike on the target. 98 % of the K.E. is used up to produce heat energy and the remaining energy appears in the form of X – ray.

Intensity of X – rays :-

The intensity of X – rays depends upon the no. of electrons produced at cathode and the no. of electrons depends upon the current flowing through it. Hence, intensity of X – ray can be increased or decreased by increasing or decreasing the current flowing through cathode.

Quality of X – rays :-

Quality of X – ray depends on the kinetic energy of electrons by which it strikes the target. And the K.E. of electron depends on the potential difference between cathode and anode. Hence, quality of X – ray depends on potential difference between cathode and anode.

eV = ½ mv²