What is Electronic Charge
An electronic charge may be considered as a collection of electrons.
The unit of electronic charge is the coulomb (symbol C), equal to the total charge on 6.242 × 1018 electrons.
1 coulomb = 6.242 × 1018qe
where qe is the charge on an individual electron.
A charge created by a surplus of electrons is negative. Materials are normally electrically neutral, that is, the positive and negative charges balance out. A charge created by a deficiency of electrons is then positive.
The charge is known as static electricity because the charge is stationary – until it is discharged.
What is Voltage
Voltage is defined in terms of the work required to move a charge between two points at different potential.
One volt is the potential difference between two points when the work required to move one coulomb of charge between them is one joule.
In equation form:
W = QV
where V is the voltage difference between two points, Q is the charge being moved in coulombs, and W is the work in joules.
What is Current
An electrical current is measured in amperes. One ampere of current is equivalent to the flow of one coulomb of charge per second.
That is:
I = Q / t
where I is the current in amperes, Q is the charge in coulombs and t the elapsed time in seconds.
What is Resistance
Current is proportional to (increases with) voltage V . The constant of proportionality is the conductance, symbol G, measured in siemens.
I = GV
Conductance is somewhat useful, but its inverse, resistance R. In other words, Resistance is a measure of the opposition to current flow in an electrical circuit. It is measured in ohms (greek symbol Ω).
R = 1/G Ω
Then the current and voltage relationship using resistance is
I = V/R
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| Resistance in DC Circuit |
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