Admittance (Y) :-
An admittance of a linear constant-parameter system is the ratio of the phasor equivalent of the steady-state sine-wave current or current-like quantity (response) to the phasor equivalent of the corresponding voltage or voltage-like quantity (driving force).
Capacitance (C) :-
Capacitance is that property of a system of conductors and dielectrics which permits the storage of electrically separated charges when potential differences exist between the conductors. Its value is expressed as the ratio of an electric charge to a potential difference.
Coupling Coefficient (k) :-
Coefficient of coupling (used only in the case of resistive, capacitive, and inductive coupling) is the ratio of the mutual impedance of the coupling to the square root of the product of the self-impedance of similar elements in the two circuit loops considered.
Conductance (G):-
1. The conductance of an element, device, branch, network, or system is the factor by which the mean-square voltage must be multiplied to give the corresponding power lost by dissipation as heat or as other permanent radiation or as electromagnetic energy from the circuit.
2. Conductance is the real part of admittance.
Conductivity (g) :-
The conductivity of a material is a factor such that the conduction current density is equal to the electric field strength in the material multiplied by the conductivity.
Current (I) :-
Current is a generic term used when there is no danger of ambiguity to refer to any one or more of the currents described below. (For example, in the expression “the current in a sim- ple series circuit,” the word current refers to the conduction current in the wire of the inductor and to the displacement current between the plates of the capacitor.)
Conduction Current :-
The conduction current through any surface is the integral of the normal component of the conduction current density over that surface.
Displacement Current :-
The displacement current through any surface is the integral of the normal component of the displacement current density over that surface.
Current Density (J) :-
Current density is a generic term used when there is no danger of ambiguity to refer either to conduction current density or to displacement current density or to both.
Displacement Current Density:-
The displacement current density at any point in an electric field is (in the International System) the time rate of change of the electric-flux-density vector at that point.
Conduction Current Density:-
The electric conduction current density at any point at which there is a motion of electric charge is a vector quantity whose direction is that of the flow of positive charge at this point, and whose magnitude is the limit of the time rate of flow of net (positive) charge across a small plane area perpendicular to the motion, divided by this area, as the area taken approaches zero in a macroscopic sense, so as to always include this point. The flow of charge may result from the movement of free electrons or ions but is not in general, except in microscopic studies, taken to include motions of charges resulting from the polarization of the dielectric. Damping Coefficient (d).
Elastance (S) :-
Elastance is the reciprocal of capacitance.
Electric Charge, Quantity of Electricity (Q): -
Electric charge is a fundamentally assumed concept required by the existence of forces measurable experimentally. It has two forms known as positive and negative. The electric charge on (or in) a body or within a closed surface is the excess of one form of electricity over the other.
Electric Constant, Permittivity of Vacuum (Γe):-
The electric constant pertinent to any system of units is the scalar which in that system relates the electric flux density D in vacuum, to E, the electric field strength. It also relates the mechanical force between two charges in vacuum to their magnitudes and separation.
Electric Field Strength (E):-
The electric field strength at a given point in an electric field is the vector limit of the quotient of the force that a small stationary charge at that point will experience, by virtue of its charge, as the charge approaches zero.
Electric Flux (Ψ): -
The electric flux through a surface is the surface integral of the normal component of the electric flux density over the surface.
Electric Flux Density, Electric Displacement (D):-
The electric flux density is a quantity related to the charge displaced within a dielectric by application of an electric field. Electric flux density at any point in an isotropic dielectric is a vector which has the same direction as the electric field strength, and a magnitude equal to the product of the electric field strength and the permittivity. In a non isotropic medium,may be represented by a tensor and D is not necessarily parallel to E.
Electric Polarization (P):-
The electric polarization is the vector quantity defined by the equation P = (D - Γe E)/Γr, where D is the electric flux density, Γe is the electric constant, E is the electric field strength, and Γr is a coefficient.
Electrization (Ei):-
The electrization is the electric polarization divided by the electric constant of the system of units used.
Electrostatic Potential (V):-
The electrostatic potential at any point is the potential difference between that point and an agreed-on reference point, usually the point at infinity.
Electrostatic Potential Difference (V):-
The electrostatic potential difference between two points is the scalar-product line integral of the electric field strength along any path from one point to the other in an electric field, resulting from a static distribution of electric charge.
Impedance (Z):-
An impedance of a linear constant-parameter system is the ratio of the phasor equivalent of a steady-state sine-wave voltage or voltage-like quantity (driving force) to the phasor equivalent of a steady-state sine-wave current or current-like quantity (response). In electromagnetic radiation, electric field strength is considered the driving force and magnetic field strength the response. In mechanical systems, mechanical force is always considered as a driving force and velocity as a response. In a general sense, the dimension (and unit) of impedance in a given appli- cation may be whatever results from the ratio of the dimensions of the quantity chosen as the driving force to the dimensions of the quantity chosen as the response. However, in the types of systems cited above, any deviation from the usual convention should be noted.
Mutual Impedance:-
Mutual impedance between two loops (meshes) is the factor by which the phasor equivalent of the steady-state sine-wave current in one loop must be multiplied to give the phasor equivalent of the steady-state sine-wave voltage in the other loop caused by the current in the first loop.
Self-impedance:-
Self-impedance of a loop (mesh) is the impedance of a passive loop with all other loops of the open-circuited network.
Transfer Impedance: -
A transfer impedance is the impedance obtained when the response is determined at a point other than that at which the driving force is applied.
Magnetic Constant, Permeability of
Vacuum (Γm):-
The magnetic constant pertinent to any system of units is the scalar which in that system relates the mechanical force between two currents in vacuum to their magnitudes and geometric configurations.
Magnetic Field Strength (H):-
Magnetic field strength is that vector point function whose curl is the current density and which is proportional to magnetic flux density in regions free of magnetized matter.
Magnetic Flux (Φ):-
The magnetic flux through a surface is the surface integral of the normal component of the magnetic flux density over the surface.
Magnetic Flux Density, Magnetic Induction (B) :-
Magnetic flux density is that vector quantity which produces a torque on a plane current loop in accordance with the relation T = IAn × B, where n is the positive normal to the loop and A is its area. The concept of flux density is extended to a point inside a solid body by defining the flux density at such a point as that which would be measured in a thin disk-shaped cavity in the body centered at that point, the axis of the cavity being in the direction of the flux density.
Magnetic Moment (m) :-
The magnetic moment of a magnetized body is the volume integral of the magnetization. The magnetic moment of a loop carrying current I is m = (1/2)∫ r × dr, where r is the radius vector from an arbitrary origin to a point on the loop, and where the path of integration is taken around the entire loop.
Magnetic Polarization, Intrinsic Magnetic Flux density (J, Bi): -
The magnetic polarization is the vector quantity defined by the equation J (B ΓmH)/Γr, where B is the magnetic flux density, Γm is the magnetic constant, H is the magnetic field strength, and Γr is a coefficient that is set equal to unity in a rationalized system and to 4 in an unrationalized system.
Magnetic Susceptibility (χm): -
Magnetic susceptibility is the quantity defined by χm(µr-1)/Γr, where µr is the relative permeability and Γr is a coefficient that is set equal to unity in a rationalized system and to 4 in an unrationalized system.
Magnetic Vector Potential (A):-
The magnetic vector potential is a vector point function characterized by the relation that its curl is equal to the magnetic flux density and its divergence vanishes.
Magnetization (M, Hi) :-
The magnetization is the magnetic polarization divided by the magnetic constant of the system of units used.
Magnetomotive Force (Fm):-
The magnetomotive force acting in any closed path in a magnetic field is the line integral of the magnetic field strength around the path.
Mutual Inductance (M):-
The mutual inductance between two loops (meshes) in a circuit is the quotient of the flux linkage produced in one loop divided by the current in another loop, which induces the flux linkage.
Permeability:-
Permeability is a general term used to express various relationships between magnetic flux density and magnetic field strength. These relationships are either (1) absolute permeability (µ), which in general is the quotient of a change in magnetic flux density divided by the
corresponding change in magnetic field strength, or (2) relative permeability (µr), which is the ratio of the absolute permeability to the magnetic constant.
Permeance (Pm):-
Permeance is the reciprocal of reluctance.
Permittivity, Capacitivity:-
The permittivity of a homogeneous, isotropic dielectric, in any system of units, is the product of its relative permittivity and the electric constant appropriate to that system of units.
Relative Permittivity, Relative Capacitivity, Dielectric Constant ( r): -
The relative permittivity of any homogeneous isotropic material is the ratio of the capacitance of a given configuration of electrodes with the material as a dielectric to the capacitance of the same electrode configuration with a
vacuum as the dielectric constant. Experimentally, vacuum must be replaced by the material at all points where it makes a significant change in the capacitance.
Power (P) :-
Power is the time rate of transferring or transforming energy. Electric power is the time rate of flow of electrical energy. The instantaneous electric powerat a single terminal pair is equal to the product of the instantaneous voltage multiplied by the instantaneous current. If both voltage and current are periodic in time, the time average of the instantaneous power, taken over an integral number of periods, is the active power, usually called simply the power when there is no danger of confusion.
If the voltage and current are sinusoidal functions of time, the product of the rms value of the voltage and the rms value of the current is called the apparent power;the product of the rms value of the voltage and the rms value of the in-phase component of the current is the active power; and the product of the rms value of the voltage and the rms value of the quadrature component of the current is called the reactive power. The SI unit of instantaneous power and active power is the watt. The germane unit for apparent power is the volt-ampere and for reactive power is the var.
Power Factor:-
Power factor is the ratio of active power to apparent power.
Reactance (X):-
Reactance is the imaginary part of impedance.
Reluctance (Rm): -
Reluctance is the ratio of the magnetomotive force in a magnetic circuit to the magnetic flux through any cross section of the magnetic circuit.
Reluctivity:- Reluctivity is the reciprocal of permeability.
Resistance (R):-
1. The resistance of an element, device, branch, network, or system is the factor by which the mean- square conduction current must be multiplied to give the corresponding power lost by dissipation as heat or as other permanent radiation or as electromagnetic energy from the circuit.
2. Resistance is the real part of impedance.
Resistivity (r):-
The resistivity of a material is a factor such that the conduction current density is equal to the electric field strength in the material divided by the resistivity.
Self-inductance (L)
1. Self-inductance is the quotient of the flux linkage of a circuit divided by the current in that same circuit which induces the flux linkage. If voltage induced, d(Li)/dt.
2. Self-inductance is the factor L in the 1/2Li2 if the latter gives the energy stored in the magnetic field as a result of the current i.
Susceptance (B):-
Susceptance is the imaginary part of admittance.
Transfer Function (H):-
A transfer function is that function of frequency which is the ratio of a phasor output to a phasor input in a linear system.
Transfer Ratio (H): -
A transfer ratio is a dimensionless transfer function.
Voltage, Electromotive Force (V): -
The voltage along a specified path in an electric field is the dot product line integral of the electric field strength along this path. As defined, here voltage is syn- onymous with potential difference only in an electrostatic field.
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