Foundations of electrical quantities: which statement best defines voltage (also called electric potential difference) in basic circuit theory?

Introduction / Context:
Voltage, current, and resistance are the three primary electrical quantities used throughout electronics. Confusing these terms leads to incorrect reasoning and design mistakes. This question asks for the definition of voltage in clear, practical terms relevant to basic circuits.

Given Data / Assumptions:

• Voltage is measured in volts (V).
• It is defined between two points (potential difference).
• It motivates charges to move when a conductive path is available.

Concept / Approach:
Voltage is analogous to pressure in fluid systems: it represents the potential to do electrical work by moving charges. When a circuit is closed, voltage across a component drives current through it according to Ohm’s law I = E / R. Current, by contrast, is the actual flow of charge (measured in amperes). Statements about particles or electron counts are unrelated to the definition of voltage.

Step-by-Step Solution:

Verification / Alternative check:
Examples: a 9 V battery has a 9-volt potential difference between its terminals. Connected across a resistor, it produces current I = 9 / R. Without a closed path, potential exists but no current flows, consistent with the “cause” role of voltage.

Why Other Options Are Wrong:

Common Pitfalls:
Using “voltage” and “current” interchangeably. Always remember: voltage is a potential difference; current is movement of charge due to that potential when a path exists.

Final Answer:
The force that causes electrons to flow (potential difference between two points)