N

n type - a type of semiconductor where the current is carried mainly by electrons
nadir - point on the celestial sphere exactly opposite the zenith (lowest point)
naked eye object - an object in the sky visible with the unaided eye (down to about magnitude 6)
NAND - a logic gate that gives a high output when the two inputs are not both high
nano - one thousand millionth (10^-9)
nanometre - one thousand millionth of a metre (10^-9 m). Useful unit for wavelength of light
near point - closest point to the eye that can be comfortably focused on (about 25 cm away)
nebula - astronomical object - fuzzy blob in small telescope - gaseous or galaxy
negative feedback - feedback that tends to reduce the output
negligible - too small in comparison with other things to be worth considering or allowing for
neodymium - highly magnetic metallic material use for magnets
Neptune - the eighth planet from the Sun
net - resultant, as in 'net force', final force after a set of forces has been added, left over
neutral - with no electrical charge
neutral point - point where fields (usually magnetic) cancel out to give zero field
neutrino - fundamental particle with no charge and 'near zero' mass
neutron - neutral particle with a mass a little greater than a proton. Found in nuclei.
neutron number - the number of neutrons in a nucleus
neutron star - a small, very dense star. Mostly neutrons. Remnant of a supernova explosion
Newton - unit of force (N)
newtonian - type of reflecting telescope with curved main mirror and flat secondary
nichrome - an alloy with a high resistivity and melting point
node - point of zero vibration in a standing wave, as at the ends of a guitar string
noise - background unwanted signals in a receiver
NOR - logic gate giving a high output when neither of the two inputs is high
NOT - logic gate giving a high output when the input is low
normal - perpendicular, as in the 'normal line' perpendicular to a mirror
nova - a 'new' star that has suddenly increased its brightness (see supernova)
nucleon - particle in the nucleus of an atom, e.g. proton or neutron
nucleus - positively charged centre of an atom . Composed of protons and neutrons
nuclide - a type of atom described by its proton and neutron number