Electronic devices operate by the movement of electrons through
conductors, e.g. wires, and electronic components. The quantity,
rate of flow, and driving force for electrons are described by
the following basic quantities. Symbol: q, unit: coulomb (C)
Charge is an amount of electrons. One coulomb is the charge of
6x1018 electrons. Symbol: I, unit: ampere or amp (A) Current is
the rate of flow of charge, i. e., the number of coulombs
flowing past a point per second. One amp is equal to one coulomb
per second. Symbol: V or E, unit: volt (V) Voltage (also called
potential, potential difference, potential drop, or
electromotive force - EMF) is the electronic potential energy
between two points, and is the driving force that causes charge
to flow. One volt is defined as the potential difference that
requires one joule of energy to move one coulomb of charge.
Voltage is always measured relative to some other point in a
circuit, e.g., the potential across a resistor. Voltage
measurements made at a single point in a