Showing posts with label Field. Show all posts
Showing posts with label Field. Show all posts


 A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

<Prev>                   <Next> 

Fermi Level

It determines probability of occupancy of allowed energy states.


It is unit of wave length used in nuclear physics which is named after Italian physicist Enrico Fermi. One Fermi is equal to one Femto meter i.e. 10-15 meter.


Elementary particles which obey Fermi Dirac statistics having spin ½. They fall in two main classes according to whether they are lighter than mesons or heavier. The two classes are Leptons or Baryons respectively.


Ceramic oxide materials composed of both divalent and trivalent cations.


In some materials (e.g., Fe, Ni, Co) the non – zero atomic magnetic dipoles interact with one another and spontaneously produce magnetization over small domains of sizes of few microns. The different domains may have random orientations resulting in zero bulk magnetic moment. Macroscopic magnetization arises when the domains are made to align themselves in a common direction. In ferromagnetic materials for each value of magnetization, there is no unique value of the field B; it depends on the history by which the magnetization is reached. This is the phenomenon of hysteresis.


Phenomenon exhibited by a group of dielectric materials which exhibit spontaneous polarization i.e. polarization in absence of an electric field. They are dielectric analogue of ferromagnetic materials. In ferroelectric materials, permanent electric dipoles exist.   

Ferrous Alloy

A metal alloy for which iron is the prime constituent.

Fick’s first Law

The diffusion flux is proportional to concentration gradient.

J=-D(dc/dx); the law holds good for steady state diffusion situations. The negative sign indicates that ‘J’ is positive when movement is down the gradient. ‘D’ is diffusivity or diffusion coefficient.

Fick’s Second Law

The time rate of change of concentration is proportional to second derivative of concentration. This law is employed in non-steady state diffusion situations.

Fictious Force (Pseudo force)

It is force which does not act on object but appears due to acceleration of non inertial frame of reference.


A property of a point in space describing the forces that would be exerted on particle, if it was there.


Any physical quantity which takes different values at different points in space and time.

Fine Structure Constant

The amount of splitting of main spectral lines of atom is characterized by dimensionless constant called fine structure constant. The value is nearly equal to 1/137.

Fine Structure

The splitting of main spectral lines of an atom in to two or more components each representing slightly different wavelength is called as fine structure. It is actually produced when an atom emits light in making the transition from one energy state to another. The fine structure of main lines arise from the interaction of orbital motion of an electron with the quantum mechanical spin of that electron.


Nuclei that can undergo fission when neutron impinges on them are called fissile nuclei.

Fission Chamber

Fission chambers use neutron-induced fission to detect neutrons. The chamber is usually similar in construction to that of an ionization chamber except that the coating material is highly enriched U-235. The neutrons interact with the

U-235, causing fission. One of the two fission fragments enters the chamber while the other fission fragment embeds itself in the chamber wall.

Flint Glass

An optical glass developed by George Ravenscroft in 1675. Flint glass is any highly refractive Lead containing glass used to make lenses & prisms. It has got high dispersion (low abbe number).


The flux integrated over a period of time is called as integrated flux or fluence. Mathematically, it is given by Φ=dN/da; where, dN represents the number of particles passing through the area ‘da’. Since this relation does not explicitly contain time, it can also be interpreted to represent the number of particles incident on a surface area ‘da’ at any instant.

Fluid Pressure

It is normal force per unit area of surface. Surface may be a body immersed in fluid or any imaginary surface with in fluid.


Substances capable of flowing are fluids. They don’t have any fixed shape of their own. They take shape of containing vessel.

All about Force?

Force definition

The push or pull of a body by an object is called force on the body.


Force is an external influence acting on a body to change its state of motion.

Types of Forces

Contact Force 

Force which results when there is a direct physical contact between two interacting objects is known as contact force. 

Types of Contact Forces

Muscular Force
The force which we exert by using our muscles is called as muscular force.

Friction Force
The force which resists the motion of an object over the surface of other.  The direction of friction force is always opposite to the direction of the motion relative to the surface.

Normal Force
The friction force, on an object, which acts perpendicular to the surface of  its plane is called as Normal Force. 

Tension is a pulling force acting on a object by means of a string against the gravitational force.  

Field Force

The force which occurs without any physical contact is known as force at a distance or field force.

Field is region of imaginary lines around an object. When an other body is placed in this region, it will experience the force. The greater the density of these imaginary lines, the stronger the forces in that region.

Types of Field Forces

Magnetic Force
Magnetic force is a field force responsible for attraction of like poles and repulsion of unlike poles.

Electrostatic Force
Force exerted by a charged body on another charged body is known electrostatic force. This force is due to electric field from the charge.

Gravitational Force
The force of attraction that exists between any two masses n the universe is known as Gravitational force. This force is due to electric field from the charge. Gravitational force is also non contact force and hence it is also a field force.

Net Force

Multiple forces can act on an object simultaneously at a time. When the forces act in same direction then net force will be addition of all forces. When the forces are in opposite direction, then net force will be difference of the forces. When the Net force is zero, there is no change in state of object. 

The direction of motion of the object will be in the direction of Net Force. If the Net Force acts in direction of motion, the speed of the an object moving with constant speed also increase. If the Net Force acts in a direction opposite to the motion, then it either slows down the object or brings it to rest or it may change the direct of motion. 

The unit of force in SI system is Newton(N). 


The force acting perpendicularly on unit area of a surface is called as pressure.

Pressure = Force/Area

The unit of pressure in SI system is Newton/Meter² or N/m²