**"A
Special Consideration of Capacitors and Coils", **

**"Controlled
Current Sources" (06/01/2021)
**

__Key
words:__

Rate of Flow & Container Volume (Capacity)

Rate of Change of Voltage vs Amount of Current Flow

Rate of Change of Current vs CEMF

__Review
of some definitions:__

1Ampis a flow of 1 Coulomb per second

1Coulomb(besides being a quantity) is 6.24 x 10^{18 }electrons (i.e. a "bucket-full")

1Faradwill hold 1 Coulomb at 1 Volt

1Henrywill develop 1 Volt CEMF against a change of 1 ampere per second, as a Rate of Change

A Constant-Voltage Source requires a Low-Internal Resistance, and supplies whatever current is needed,

while a Constant-Current Source has a High-Internal Resistance and supplies whatever voltage is needed.

__New Considerations:__

Capacitors depend on a "Dialectric" between the Conductive Elements to increase the Charge Amount.The property of this Dialectric, depending on the substance or material ,

varies as it's "Permitivy" (not to be confused with Permeability),

also known as it's"Dialectric Index", which determines it's ability to hold a charge.

__Things
to look for:__

We are going to discover a case where aconstant Voltage causes a rate change, and

we are going to discover another case where arate change causes a constant Voltage.

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**Remember
that Capacitors react to voltage changes by drawing or discharging
current, and**

**that
Inductors react to changes in current by opposing the voltages by
CEMF, but**

**what
happens to a Capacitor if we deliberatly control the current being
fed to a capacitor?**

**And what
happens to the CEMF of an Inductor if we don't change the current?**

**What
determines the CEMF of an Inductor if we increase or decrease the
rate of change?**

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*Now,
where are we going with this?*

*How
about an **ultra-simple
example** for a start:*

__Example:__

Imagine a container for compressed dry air, with a pump supplying aflowof air at a consistantrate.

The container not only consists ofvolume, but alsopressure build at a predicatable value.

**= = = = = = = = = = = = = = = = = = =
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
= = = = = = = = = = =**

Feeding a Capacitor with a Constant Current

**Now,
if we take a capacitor with a known "Capacity", totally
discharged, and feed this capacitor with a ****"Constant
Current"****,
**

**it will charge at a determined linear ****"Rate
of Change"****
of the Voltage.**

*Note
that here a constant current will cause a "Rate of Change of the
Voltage" of the Capacitor.*

*(As
there is a collection of electrons on one side and displacement of
electrons on the other side)*

**If
we alter the value of the ****"Constant
Current"****,
we will find that the ****"Rate
of Change"****
of the charging voltage (i.e. The slope) will change accordingly.**

__Feeding
a Capacitor with a Changeable, but Otherwise Constant Current__

**Note
particullary that the "Rate of Change" (i.e. Rate of
Charge) will be altered to be less (lower slope) or more (higher
slope), depending on the actual value of current.**

__Final
Note:__

*With
the Capcitor, the "Rate of Change" (of the Capacitor's
Voltage) occurs depending on the value of the charging current***.**

**= = = = = = = = = = = = = = = = = = =
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
= = = = = = = = = = =**

__Feeding
an Inductor with a Constant Current__

**Once
a current value is established, and stays constant, there will be no
CEMF created.**

**As
the Inductor is not a storage unit, ther is no "Collective
Value" to consider, ****except with the energy stored in the
magnetic field.**

__Feeding
an Inductor with an Increasing Current "Rate of Change"__

**However,
if current is being increased at a ****linear
rate****,
the CEMF with be a ****constant
value****,
based on the ****"Rate
of Change"****
and the ****"Inductive
Value"****.
**

**If the"Rate of Change" is ****doubled****,
the amount of CEMF will also ****double**.

**Note
particullary that the "Rate of Change" (i.e. Rate of
Current Change, as a higher or lower slope) will cause a "Consistant
CEMF" of the Inductor**.

__Final
Note:__

*With
the Inductor, the "Rate of Change" (of the increase or
decrease of current) will determine the "*__Constant
Value of the CEMF__*"*

**A
Special Consideration of Capacitors and Coils – ddf –
WA7RSO – 06/01/2021**