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Return to Terminology
Q
- Qualification Tests
- A series of tests conducted on an item or system to determine
if it meets the requirements established for the specified use.
- Quality Assurance
- System of assuring that material accepted is in accordance
with requirements, including inspection and test procedures, acceptance criteria, etc.
- Quantity - Distance Table
- A table listing minimum recommended distances from explosive
materials stores of various weights to a specific location.
- Quantum Theory
- Quantum theory, modern physical theory that holds that energy
and some other physical properties often exist in tiny, discrete amounts. The older
theories of classical physics assumed that these properties could vary continuously.
Quantum theory and the theory of Relativity together form
the theoretical basis of modern physics. The first contribution to quantum theory was the
explanation of blackbody radiation in 1900 by Max Planck, who proposed that the energies
of any harmonic oscillator are restricted to certain values, each of which is an integral
multiple of a basic minimum value. The energy E of this basic quantum is directly
proportional to the frequency n of the oscillator; thus E = hn, where Planck's constant h
is equal to 6.63 x 10-34 J-sec. In 1905 Albert Einstein, in order to explain the Photoelectric
Effect, proposed that radiation itself is also quantized and consists of light quanta,
or Photons, that behave like particles. Niels Bohr
used the quantum theory in 1913 to explain both atomic structure and atomic spectra. The
light or other radiation emitted and absorbed by atoms is found to have only certain
frequencies (or wavelengths), which correspond to the absorption or emission lines seen in
atomic spectra ( Spectrum). These frequencies correspond to
definite energies of the photons and result from the fact that the electrons of the atoms
can have only certain allowed energy values, or levels. When an electron changes from one
allowed level to another, a quantum of energy is emitted or absorbed whose frequency is
directly proportional to the energy difference between the two energy levels E1 and E2;
thus E2 - E1 = hv. Quantum mechanics, the application of the quantum theory to the motions
of material particles, was developed during the 1920s. In 1924 Louis de Broglie proposed
that not only does light exhibit particle-like properties but also particles may exhibit
wavelike properties. The observation, by Clinton Davisson and Lester Germer in a 1927
experiment that the diffraction of a beam of electrons is analogous to the diffraction of
a beam of light confirmed this hypothesis. A particularly important discovery of the
quantum theory is the uncertainty principle, enunciated by Werner Heisenberg in 1927; it
places an absolute, theoretical limit on the combined accuracy of certain pairs of
simultaneous, related measurements.
- Quasar
- Quasar or quasi-stellar object, one of a class of faint blue
celestial objects, starlike in appearance, that are currently believed to be the most
distant and most luminous objects in the universe. The spectral lines of quasars have
enormous Red Shifts that seem to imply that they are
receding from our galaxy with speeds as great as 80% of the speed of light. If Hubble’s
Law for the expansion of the universe is extrapolated to include quasars, they may be
as far as 8 billion Light-Years away and consequently as luminous intrinsically as
100 galaxies combined.
- Quickness
- Rate of change of pressure within the closed chamber with
respect to time.
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