Technological I-Wps Office

ELECTROSTATICS
Electrostatics is the physics term for a static charge.

Electro means a charge, and of course, static means stationary or
not moving.
Electric charge is the physical property of matter that causes it to
experience a force when placed in an electromagnetic field. There
are two types of electric charge: positive and negative (commonly
carried by protons and electrons respectively). Like charges repel
each other and unlike charges attract each other.

Charging – the process of adding or removing electrons
 Conduction – direct contact
 Induction – indirect contact
Coulomb’s Law
First Law of Electrostatics: Like charges repel each other and

unlike charges attract each other.
Second Law of Electrostatics: The force of attraction or

repulsion between charges is directly proportional to the
product of two charges and inversely proportional to the square
of the distance between them.

Electric permittivity is something similar
to conduction that tells us how easily an
electric field can pass through a
substance.
Electric permittivity is a measure of how
well the molecules of substance align, a.k.
Electric a. polarize, under an electric field. The
higher the electric permittivity the better
permittivity the molecules polarize and the more that
substance resists the external electric
field.
Dielectric, insulating material or a very

poor conductor of electric current.
Source:
https://www.youtube.com/watch?v=F6DhNsmz_30
Electric field
The electric field is the region

around the charged particle
within which the other charges
experience the force of
attraction or repulsion.
Example 1:
Two point charges of 2 C and a 5 C are 10 meters apart. What is the
force between the two charges?
Electrostatic potential
Electric Field
Intensity

Electric field intensity –
the force per unit charge
that will act at a point in
the field on a very small
test charge placed at that
location.
where: E = electric intensity in newton per coulomb (N/C)
d = distance in meters of the test charge (1 C) to the
charge (+Q ) body.
Electric field outside an
isolated sphere in free space
where: E = electric field intensity (volt per meter) at a
distance r (meter) from the center of an isolated charged
sphere located in free space.
Q = total charge (coulomb) which is distributed
uniformly on the sphere.

Electric Field Intensity
created by an isolated ,
charged long
cylindrical wire in free
Space
Electric Flux Density
Electric flux density is a measure of the strength of

an electric field generated by a free electric charge,
corresponding to the number of electric lines of force passing
through a given area. Electric flux density is the amount
of flux passing through a defined area that is perpendicular to the
direction of the flux.
where: D = electric flux density (coulomb per square meter)
Capacitance is the ratio of the amount
of electric charge stored on a conductor to
a difference in electric potential.
There are two closely related notions of
capacitance: self-capacitance and mutual
Capacitanc capacitance.

e Any object that can be electrically charged

exhibits self-capacitance. In this case, the
electric potential difference is measured
between the object and the ground. A
material with a large self-capacitance holds
more electric charge at a given potential
difference than one with low capacitance.
The notion of mutual capacitance is particularly important for
understanding the operations of the capacitor, one of the three
elementary linear electronic components (along
with resistors and inductors).
In a typical capacitor, two conductors are used to separate electric
charge, with one conductor being positively charged and the other
negatively charged, but the system has a total charge of zero. The
ratio in this case is the magnitude of the electric charge on either
conductor and the potential difference is that measured between the
two conductors.
Capacitance is a measure of how well a capacitor can store electric
charges.

Capacitor (old name is condenser) – any device on which electric
charges can be stored so as to possess electric potential. It
consists of two conducting plates separated by a layer of an
insulating medium called dielectric.

Farad (F) - unit of capacitance when one coulomb of charge
given to its plates raises it potential difference by one volt.
Named after the British physicist and chemist who discovered
electromagnetic induction, Michael Faraday (1791 – 1867).
where: C = capacitance of a charge
capacitor (farad)
Q = charge stored (coulomb)
E = voltage across the
capacitor (volt).
Capacitance of
a two parallel-
plate capacitor
with a uniform
dielectric
medium.
Capacitance of an Isolated Sphere
Capacitance of a concentric spherical
capacitor
Capacitanc
e of a
coaxial
cable (farad
per meter)
Capacitance of
two -wire line
(parallel-cylinder
capacitor) with
opposite
charges (farad
per meter)

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ELECTROSTATICS

Electrostatics is the physics term for a static charge.

First Law of Electrostatics: Like charges repel each other and

Second Law of Electrostatics: The force of attraction or

Dielectric, insulating material or a very

The electric ﬁeld is the region

Electric ﬂux density is a measure of the strength of

e Any object that can be electrically charged

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