n-type semiconductor – a doped semiconductor in which impurity atoms have increased the number of negative carriers

Natural frequency – the frequency of oscillation that, once begun, will continue without a driving force if no damping forces are present

Natural period– period of an oscillator oscillating at its natural frequency

Near point - the shortest distance from the unaided eye that produces a distinct (focused) image on the retina

Net force – the vector sum of all forces acting simultaneously on an object

Neutrino – a weak neutral particle emitted during beta decay

Neutron – an elementary particle, similar to a proton, but with a neutral charge

Newton – the SI unit of force (a kilogram meter/ second squared)

Newtonian mechanics – the branch of physics which deals with kinematics and the dynamics of large-scale (macroscopic) objects

Newtonian telescope – a telescope in which the objective lens has been replaced by a concave mirror (see figure 23.11)

Node – a point of zero vibrational amplitude

Normal force - a force perpendicular to the surface of contact (when two objects are touching)

Nucleus – the positively charged center of an atom where most of the atom's mass resides