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Fundamentals of Electric Capacitors
In the development and manufacturing of capacitors and their applications, several properties must be considered for dielectric materials including
dielectric strength, dielectric constant, leakage current, power and quality
factors, operating temperature, and breakdown voltage.
1.4 Capacitor Charging and Recharging Processes
Charging a capacitor is done by integrating it into an electrical circuit containing an external power source (i.e., a battery). When the circuit is a closed
loop, the battery will provide an electromotive force (emf) to generate a flow
of electrons through the circuit. During this process, the positive capacitor
plate loses electrons to the positive terminal of the battery, thus making the
plate positively charged. Simultaneously, electrons flowing from the negative
terminal of the battery accumulate on the capacitor’s negative plate, making
it negatively charged. The number of electrons accumulated on the negative
electrode is exactly equal to the number of positive charges accumulated
on the positive electrode. The charging process continues until the potential
between the plates that was initially zero is equal to the potential difference
between the battery terminals. The capacitor is then said to be fully charged
in reference to the driving potential.
1.4.1 DC and AC Currents
Due to charging and discharging, a capacitor needs a charge flow within the
plate through an external wire. This electric flow is called electric current,
defined as the flow of electric charge across a defined point or area and measurable in units of Coulombs per second [C/s 1 , also called amperes (A)]. The
perception is that a current is produced by the electrons traveling through
a conducting wire medium, but ions transported through a medium (electrolyte) can also produce current. This discussion will focus on the flow of
electrons through solid metallic conductors.
In metal, electrons are negative and singularly mobile charges that flow
in the direction of an electric potential gradient from a lower potential to
a higher one. This potential gradient, commonly called electromotive or
driving force, is primarily responsible for the work necessary for the travel
of electrons through a closed electric circuit or more importantly, with a
connected electric load. In electric circuit analysis, the current direction
is the direction of the positive charge flow rather than the electron charge
flow. In a metal electric wire, only electrons are mobile to produce current.
Therefore, the electron flow direction is opposite to the current direction.
The current can be constant or momentary and classifying a current is
Fundamentals of Electric Capacitors
In the development and manufacturing of capacitors and their applications, several properties must be considered for dielectric materials including
dielectric strength, dielectric constant, leakage current, power and quality
factors, operating temperature, and breakdown voltage.
1.4 Capacitor Charging and Recharging Processes
Charging a capacitor is done by integrating it into an electrical circuit containing an external power source (i.e., a battery). When the circuit is a closed
loop, the battery will provide an electromotive force (emf) to generate a flow
of electrons through the circuit. During this process, the positive capacitor
plate loses electrons to the positive terminal of the battery, thus making the
plate positively charged. Simultaneously, electrons flowing from the negative
terminal of the battery accumulate on the capacitor’s negative plate, making
it negatively charged. The number of electrons accumulated on the negative
electrode is exactly equal to the number of positive charges accumulated
on the positive electrode. The charging process continues until the potential
between the plates that was initially zero is equal to the potential difference
between the battery terminals. The capacitor is then said to be fully charged
in reference to the driving potential.
1.4.1 DC and AC Currents
Due to charging and discharging, a capacitor needs a charge flow within the
plate through an external wire. This electric flow is called electric current,
defined as the flow of electric charge across a defined point or area and measurable in units of Coulombs per second [C/s 1 , also called amperes (A)]. The
perception is that a current is produced by the electrons traveling through
a conducting wire medium, but ions transported through a medium (electrolyte) can also produce current. This discussion will focus on the flow of
electrons through solid metallic conductors.
In metal, electrons are negative and singularly mobile charges that flow
in the direction of an electric potential gradient from a lower potential to
a higher one. This potential gradient, commonly called electromotive or
driving force, is primarily responsible for the work necessary for the travel
of electrons through a closed electric circuit or more importantly, with a
connected electric load. In electric circuit analysis, the current direction
is the direction of the positive charge flow rather than the electron charge
flow. In a metal electric wire, only electrons are mobile to produce current.
Therefore, the electron flow direction is opposite to the current direction.
The current can be constant or momentary and classifying a current is