enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Hydrodynamical helicity - Wikipedia

    en.wikipedia.org/wiki/Hydrodynamical_helicity

    Helicity is a pseudo-scalar quantity: it changes sign under change from a right-handed to a left-handed frame of reference; it can be considered as a measure of the handedness (or chirality) of the flow. Helicity is one of the four known integral invariants of the Euler equations; the other three are energy, momentum and angular momentum.

  3. Helicity (particle physics) - Wikipedia

    en.wikipedia.org/wiki/Helicity_(particle_physics)

    The helicity of a particle is positive (" right-handed") if the direction of its spin is the same as the direction of its motion and negative ("left-handed") if opposite. Helicity is conserved. [1] That is, the helicity commutes with the Hamiltonian, and thus, in the absence of external forces, is time-invariant. It is also rotationally ...

  4. Helicity basis - Wikipedia

    en.wikipedia.org/wiki/Helicity_basis

    In the Standard Model, using quantum field theory it is conventional to use the helicity basis to simplify calculations (of cross sections, for example).

  5. Metallicity - Wikipedia

    en.wikipedia.org/wiki/Metallicity

    In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-dark) matter in the universe is either hydrogen or helium, and astronomers use the word "metals" as convenient shorthand for "all elements except hydrogen and helium".

  6. Zimm–Bragg model - Wikipedia

    en.wikipedia.org/wiki/Zimm–Bragg_model

    In statistical mechanics, the Zimm–Bragg model is a helix-coil transition model that describes helix-coil transitions of macromolecules, usually polymer chains. Most models provide a reasonable approximation of the fractional helicity of a given polypeptide; the Zimm–Bragg model differs by incorporating the ease of propagation (self-replication) with respect to nucleation.

  7. Hydrogen spectral series - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_spectral_series

    Z is the atomic number, n′ (often written ) is the principal quantum number of the lower energy level, n (or ) is the principal quantum number of the upper energy level, and; is the Rydberg constant. (1.096 77 × 10 7 m −1 for hydrogen and 1.097 37 × 10 7 m −1 for heavy metals). [5] [6]

  8. Number density - Wikipedia

    en.wikipedia.org/wiki/Number_density

    Using the number density of an ideal gas at 0 °C and 1 atm as a yardstick: n 0 = 1 amg = 2.686 7774 × 10 25 m −3 is often introduced as a unit of number density, for any substances at any conditions (not necessarily limited to an ideal gas at 0 °C and 1 atm). [3]

  9. Atomicity (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Atomicity_(chemistry)

    Atomicity is the total number of atoms present in a molecule of an element. For example, each molecule of oxygen (O 2) is composed of two oxygen atoms. Therefore, the atomicity of oxygen is 2. [1] In older contexts, atomicity is sometimes equivalent to valency. Some authors also use the term to refer to the maximum number of valencies observed ...