Planck's constant, 6.62517 x 10 -27 erg . Thus, since X-rays have a smaller wavelength than visible light, they have higher energy. With their higher energy, X-rays can penetrate matter more easily than can visible light. Such a tube is illustrated here. It consists of an evacuated chamber with a tungsten filament at one end of the tube, called the cathode, and a metal target at the other end, called an anode.
Electrical current is run through the tungsten filament, causing it to glow and emit electrons.
Upon striking the atoms in the target, the electrons dislodge inner shell electrons resulting in outer shell electrons having to jump to a lower energy shell to replace the dislodged electrons. These electronic transitions results in the generation of X-rays. The first is called the Continuous spectra . The minimum wavelength decreases and the intensity increases as voltage increases. The second type of spectra, called the characteristic spectra , is produced at high voltage as a result of specific electronic transitions that take place within individual atoms of the target material.