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mujtaba4iit

Hey can anyone explain me what is permittivity of free space in electrostatics?

punnima

Vacuum permittivity $arepsilon_{0}$ (also called permittivity of free space or the electric constant) is the ratio D/E in free space.(D-electrical displacement field,E-electric field)

$arepsilon_0 stackrel{mathrm{def}}{=} rac{1}{{c}^2mu_0} approx$ 8.8541878176? × 10^?12 F/m (or C²N^-1m^-2),

c (or c₀) is the speed of light in free space.

? 0

is the magnetic constant.

rate if crrct

srini

Hey,

Vacuum permittivity, referred to by international standards organizations as the electric constant, and denoted by the symbol ?₀, is a fundamental physical constant relating the mechanical quantities (time, length, mass) to the units for electrical charge for example, in Coulomb's law , leading to an electric constant defined in free space by:

$\varepsilon_0 \overset{\underset{\mathrm{def}}{}}{=}\frac {1}{\mu_0 {c_0}^2} = 8.854\ 187\ 817\ldots \times 10^{-12}$ ? in A²s⁴ kg^-1m^?3 or C²N^?1m^?2 or F m^?1.

(This value is taken from NIST ?₀.) A summary of these definitions is provided in the 2006 CODATA Report.^[4]

This value is called by various other names as well, including the permittivity of free space,^[5] or of empty space,^[6] or by the term dielectric constant of vacuum^[7] (although this term is ambiguous in modern usage, as described below).

In other systems of electromagnetic units, it is common to have $\varepsilon_0 = 1$ . This is the case in Gaussian units, Lorentz?Heaviside units, and some choices of natural units (while some other choices set $\varepsilon_0 = 1/4\pi$ ,? for example, electrostatic cgs units, ).

The Coulomb force constant or electrostatic constant k_e (not a fundamental physical constant, being simply related to the fundamental constant ?₀ ) can thus be expressed as (see Coulomb's law):

$k_e\overset{\underset{\mathrm{def}}{}}{=}\frac{1}{ 4 \pi \varepsilon_0} = \frac {\mu_0 {c_0}^2}{4 \pi} = 8.987\ 551\ 787\ldots \times 10^9 \approx 9\cdot 10^9$ C^?2N¹·

source:ya you guessed...wikipedia

jinu.coolboy

shortly,it is a medium between two charges.For example in water ,air etc.

mujtaba4iit

This is just for vacuum, can anyone elaborate on any other medium.

mujtaba4iit

@jinu.coolboy, how can it be a medium?
I m really wondering!!!

srini

Hey,

as in other mediums, the force of attraction is decreased by a factor eor relative permitivity is eR

destinationIIT09

PERMITTIVITY OF AIR OR VACCUM

electrostatic force depends on the medium;to be more exact it depends on the permittivity of the medium

then there is relative permittivity

it is a property of a medium

it is defined as the ratio of permittivity of the medium to the permittivity of freespace--------------------->it is also known as dielectric constant of the medium and specific inductive capacity

mujtaba4iit

@jinu.coolboy, but what u said earlier is something very different.
U said,''it is a medium between two charges''?
Notice ur selection of words.

mujtaba4iit

Hey evry1 see srini's post, it is mentioned that vacuum permittivity is referred as electric constant,
What is permittivity of other mediums referred to?

donnowatnametochoose

How about dielectric?

punnima

Permittivity in media

In the common case of isotropic media, D and E are parallel vectors and $arepsilon$ is a scalar, but in general anisotropic media this is not the case and $arepsilon$ is a rank-2 tensor . The permittivity $arepsilon$ and magnetic permeability

of a medium together determine the phase velocity v of electromagnetic radiation through that medium:

$arepsilon mu = rac{1}{v^2}.$

kundan_leo

this is the permittivity of free space.........and your rit its known as vacuum permittivity.........because that's the standard prototype.......

synonymous to...

velocity of light in vacuum....3 . 10^8 m/sec.........standard conditions.

when we consider 2 or more media ......

relative permittivity comes into picture more commonly known as dielectric constant.........

and last known permittivity is electrical permittivity....

all 3 are related by this equation

where

E = dielectric

is the dielectric constant and

is the permittivity of free space........

hope that does it........

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Permittivity in media