N-struts (airplane wing struts). Interplane struts installed between the upper and lower wings of a biplane near the wing tips. N-struts get their name from the fact that the three pieces of these struts are arranged in the shape of the letter N.
NTAP (Notice to Airmen Publication). A publication issued every 14 days, designed primarily for the pilot, which contains current NOTAM information considered essential to the safety of flight as well as supplemental data to other aeronautical publications. The contraction NTAP is used in NOTAM text.
N-type semiconductor material. A semiconductor element, such as silicon or germanium, doped with an element having more electrons in its valence shell than are needed to complete the covalent bonds within the material. There are electrons in N-type material that are free to move about. Silicon and germanium are doped with a pentavalent element, such as arsenic or phosphorus, to make N-type material.

NTZ (no transgression zone). A 2,000-foot-wide zone, located equidistant between parallel runway final
approach courses in which flight is not allowed.
nuclear energy. Energy released when neutrons are knocked out of the nuclei of certain materials. Neutrons bind the protons together in the nucleus of an atom, and when neutrons are knocked out, the protons are then able to leave the nucleus. As they leave, they release great amounts of energy in the form of heat and light.
nuclear fission. The breaking apart of the nucleus of an atom by striking the nucleus with a neutron. If a neutron strikes the nucleus with enough force, it splits the nucleus and creates atoms of different materials. Nuclear fission releases a tremendous amount of heat and light.
nuclear fusion. A method of energy release in which a heavier nucleus is formed by fusing two lighter nuclei. When the lighter nuclei fuse, a large amount of energy is released.
nuclei. A plural form of nucleus; an alternate plural form is nucleuses.
nucleonics. The branch of science and technology that deals with nuclear energy and its applications.
nucleus of an atom. The core (center portion) of an atom. The nucleus contains one or more protons (positive charges), and all nuclei except that of hydrogen contain one or more neutrons. Neutrons have mass but no electrical charge.
null balance. A method of setting one voltage exactly equal to another. When no current flows between the two voltages, as indicated by a sensitive current-measuring instrument, the two voltages are exactly the same. The voltages have nulled out, or cancelled, each other.
null detector (electrical instrument). An instrument used to measure a value by comparing it with a known variable value. The known value is compared with the unknown and is changed until the null detector determines that there is no difference between the two. The known value is now exactly the same as that of the unknown.
null position (automatic direction finder). The position of an ADF loop antenna when the signal being received is canceled in the two sides of the loop, and the signal strength is the weakest.