Items

• nebula

  A vast cloud of gas and dust in space, often a region of star formation or the remnants of a dead star.
• negative

  A quantity less than zero; in physics, often refers to direction (e.g., negative charge, negative acceleration).
• negligible

  So small or insignificant as to be safely ignored in calculations or modeling.
• net

  The total or resultant value after all opposing factors are considered (e.g., net force = total force – opposing force).
• neutral

  Having no net charge; in chemistry and physics, refers to atoms or particles with balanced protons and electrons.
• neutrino

  An extremely light, neutral subatomic particle that interacts only via the weak nuclear force; a product of nuclear reactions.
• neutron

  A neutral subatomic particle found in atomic nuclei, with a mass slightly greater than a proton.
• nitrogen

  A colorless, odorless, inert gas making up about 78% of Earth's atmosphere. Symbol: N, Atomic number: 7.
• node

  A point in a wave or standing wave where amplitude is zero; also used in graphs and network theory.
• normal

  A line or vector perpendicular to a surface; in statistics, also refers to the "normal distribution" (bell curve).
• notation

  A system of characters, symbols, or abbreviated expressions used in an art or science or in mathematics or logic to express technical facts or quantities
• nuclear

  Of or relating to the atomic nucleus
• nucleon

  A proton or neutron especially in the atomic nucleus
• nuclide

  A species of atom characterized by the constitution of its necleus and hence by the number of protons, the number of neutrons, and the energy content.
• number

  An arithmetical value, expressed by a word, symbol, or figure, representing a particular quantity and used in counting and making calculations
• numerator

  The part of a fraction that is above the line and signifies the number to be divided by the denominator.
• observation

  An act of recognizing and noting a fact or occurrence often involving measurement with instruments.
• obstacle

  Something that impedes progress or achievement.
• octet

  A group of eight people or things.
• ohmmeter

  An instrument for measuring electrical resistance
• opaque

  Not transparent.
• optics

  A science that deals with the origin and propagation of light, the changes that it undergoes and produces, and other phenomena closely associated with it.
• orbital

  Of, relating to, or forming a circular path (such as the orbit of a moon, planet, or spacecraft).
• origin

  The point at which something begins or rises or from which it derives.
• oscillation

  The action or state of moving or travelling back and forth between two points