PHYSICS DICTIONARY

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Non-Conservative Force

If the work done by a force acting on a body depends on path followed then it is called as non-conservative force.

Non-Crystalline

The solid state where in there is no long range atomic order.

Non-Ferrous Alloy

A metal alloy for which iron is not prime constituent.

Non-Inertial Frames of Reference:

The frames relative to which an un-accelerated body appears accelerated are called non-inertial frames. All accelerated frames are non-inertial frames.

Non-Polar Dielectric

It is the substance in which the net electric dipole moment is zero because of its symmetrical structure. The center of gravity of positive and negative charges will coincide.

Normal Distribution

See Gaussian distribution

Normal Force

When two bodies are in contact or when one body is placed over another body, the contact force which either body exerts on other body normal to contact surface is called normal force or normal reaction.

Norton’s Theorem

In a linear network consisting of emfs and resistances when viewed from its output terminals, is equivalent to constant current source with parallel effective resistance. The constant current is equal to current which would flow in a short circuit placed across terminals, and the parallel resistance is resistance of network when viewed from open circuited terminals after all emfs have been removed & replaced by internal resistances.

NTP

Normal temperature and pressure is defined as air at 20^oC (293.15k) and 1atm.

N-Type Semiconductor

A type of semiconductor for which the predominant charge carriers responsible for electrical conduction are electrons.  Normally donor impurity atoms give rise to excess electrons.  

Nuclear Emulsion

Nuclear photographic emulsion, also called Nuclear Emulsion, radiation detector  generally in the form of a glass plate thinly coated with a transparent medium containing a silver halide compound. Passage of charged subatomic particles is recorded in the emulsion in the same way that ordinary black and white photographic film records a picture. After photographic developing, a permanent record of the paths of the charged particles remains and may be observed through a microscope. Radioactivity was discovered in 1896 by its effect on a photographic plate, and nuclear emulsions later played a pivotal role in cosmic-ray research—for example, in the discovery of the Pion in 1947. 

Nuclear Fission

Physical process in which a massive nucleus splits into fragments yielding high energy which gets distributed as kinetic energy of fragments and heat; this is because the sum of masses of fragments will be less than mass of nucleus. If the mass of fragments is equal to or greater than that of iron at peak of binding energy curve, then nuclear particles will be more tightly bound then they were in Uranium nucleus, and that decrease in mass comes off in form of energy according to Einstein equation.

or

It is a type of neutron interaction produced by bombardment of certain very high atomic number nuclei (Z ≥ 92) by thermal or fast neutrons. The target nucleus fragments into two daughter nuclei of lighter mass and the fission process is accompanied with production of fast neutrons. Nuclei that are capable of undergoing fission are called fissionable nuclei in general. Nuclei that undergo fission with thermal neutrons are called fissionable nuclei. Fission fragments combined with the nuclei that are subsequently formed through radioactive decay of fission fragments are called fission products. 

Nuclear Force

It holds nucleons together. It must be very strong since it mostly overcomes Coulomb force. It must have a short range of order 10^-13 cm. It holds the quarks together and also holds protons and neutrons together in nucleus of an atom. It is believed that this force is carried by another spin – 1 particle called the Gluon which interacts only with itself and with the quarks.

Nuclear Fusion

Nuclear reaction in which two or more lighter nuclei combine together to form new nucleus. In order to overcome electrostatic interaction for combination of two nuclei, high kinetic energies are required. This is usually achieved by heating matter to very high temperatures leading to plasma state.

Nuclear Magnetron

Any charged particle moving in a closed path produces a magnetic field, which at larger distance acts as due to magnetic dipole located at current loop. The protons inside the nucleus are in orbital motion and therefore produce electric currents which produce extra nuclear magnetic fields. Each nucleon possesses an intrinsic magnetic moment which is parallel to its spin and is probably caused by spinning of nucleon.

Nuclear Physics

The branch of physics which deals with study of internal structure and behavior of nucleus and its constituents. 

Nuclear Reaction

When an atomic nucleus interacts with other nuclei or particle, its structure, mass or energy gets changed. Such a process is referred to as nuclear reaction.

Nuclear Reactor

It is an arrangement used to generate power by utilizing nuclear energy. Fissionable isotopes of Uranium, Plutonium are used as fuel. Heat energy released from fission is used for converting water into steam for driving turbines to generate electricity.

Nuclear Spin

 The total angular momentum of nucleus is usually called nuclear spin.

Nucleon

The charge independence of nuclear interactions suggests that Neutron and Protons are two states of single entity, the nucleon.

Nuclide

Any nuclear species characterized by its atomic number and mass number is called as nuclide. It is conventionally denoted by where ^AX_Z; X is symbol of element; ‘A’ is mass number and ‘Z’ is called as atomic number

Nutation

The rise and fall of axis of rotation about its position of dynamic equilibrium is called as Nutation.