Electric current provides power for the x-ray tube. The low voltage circuit that connects to the cathode, allow generation of electrons through thermionic emission. The high voltage circuit accelerates the electrons from the cathode to the tungsten target. When the electrons hit the target, their kinetic energy is transformed in its majority to heat and a very small fraction is converted to x-ray. The main controls of the x-ray tube are the kilovoltage that controls the quality of the beam, the milli-amperage and exposure time control the quantity of the beam. The distance between the source of x-ray and the target controls the beam intensity. The radiographic image reflect the differential densities of the absorber (e.g., oral tissues).