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CIRCUITS PARALLEL v. SERIES RULES POWER PRACTICE PROBLEMS
voltage . . .
Current Voltage Resistance Ohm's Law
voltage
Technically, voltage is the potential difference between two points; it may also be shortened to potential or called EMF (electromotive force) when it represents the potential difference in a battery.
So, potential difference is a change in the potential energy of a charge as it is moved from one point to another then divided by the charge itself.
A metaphor for the voltage is the electric height on an energy level; positive charges then move from areas of high voltage to areas of low voltage so they figuratively roll down the voltage hill.
The power supply in a circuit acts like a ski lift, (according to the analogy) moving the charges uphill. The power supply gives the charges energy so they can move through the wires combating resistors and other objects it may encounter in the circuit. The power supply gives the charges electrical potential energy. You can measure voltage differences across the battery, resistors, the voltmeter, and other parts of the circuit.
Voltage is measured in volts V:

1 V = 1 J/C

Voltage difference requires the difference between the positive part and the negative part.

(Serway & Faughn)