• Quantum - If the magnitude of a quantity is always an integral multiple of a definite unit, then that unit is called the quantum of the electromagnetic field and the meson is considered to be the quantum of the nuclear field.
  • Quantum Mechanics - A system of mechanics based on quantum theory, which arose out of the failure of classical mechanics and electromagnetic theory to provide a consistent explanation of both electromagnetic wave and atomic structure.
  • Quantum Theory - the study of the jumps from one energy level to another as it relates to the structure and behavior of atoms.
  • Quasi-Cleavage Fracture - A fracture mode that combines the characteristics of cleavage fracture and dimpled rupture fracture. An intermediate type of fracture found in certain high-strength metal.
  • Quenching - The rapid cooling of a metal by immersing it in a bath of liquid in order to improve its properties.
  • Quenching of Fluorescence - The loss of fluorescence by causes other than the removal of the exciting radiation, for example, the action of heat, strong oxidizing agents, or strong acids or alkalis.
  • Quick-Breaking - The sudden breaking of a direct current to be induced in the part by the rapid collapse of the magnetic field. In magnetic particle testing, fast breaking of the magnetizing current in a part which is favorable for finding transverse defects at the ends of longitudinally magnetized bars. Such defects are often concealed by the strong polarity at the bar ends. At such locations the lines of force of the longitudinal field are leaving the bar in a direction normal to the surface, which prevents them from intercepting transverse defects in those areas. The field induced by the transient current does intercept such discontinuities.