electric potential

Electric potential is the amount of electrical energy stored per unit of electric charge at a given point in a field. It is measured in volts, where one volt means one joule of energy per coulomb of charge. Think of it as analogous to height in a gravitational field: just as gravity gives potential energy to a mass at height, an electric field gives potential energy to a charge at a certain location. The potential at a point tells you how much work must be done to move a unit positive charge from a reference point (usually ground, set at zero volts) to that location against the electric field.

Potential difference, or voltage, is the practical quantity you measure between two points. A 12 volt potential difference means 12 joules of energy per coulomb separates those two points. This is why voltage is fundamental to circuit design: it determines how much energy is available to push current through a resistance. In a 230 V mains supply, electrons moving through a 10 ohm load experience a potential drop that releases energy as heat at a rate given by Ohm's law and the power formula P equals V squared divided by R.

Potential and Field Strength

Electric potential and electric field strength are related but distinct. Field strength, measured in volts per meter, tells you how rapidly potential changes across space. In a uniform field between parallel plates separated by 0.1 meters at 100 volts, the field strength is 1000 V/m. The steeper the potential gradient, the stronger the field. This matters in practical terms: high field strengths near sharp corners or edges in conductors can cause ionization and breakdown, which is why high voltage equipment uses rounded surfaces and spacing calculations based on critical field strength thresholds.

In circuit and electrical machine work, you work almost entirely with potential difference rather than absolute potential, since only differences drive current and deliver power. Grounding establishes a reference point, conventionally set at zero volts, and all other potentials in the system are measured relative to it. Three phase systems have three different potentials 120 degrees apart; DC circuits have a single potential difference between conductors; transformers change potential without changing power (ignoring losses), which is essential for transmission and distribution.

The concept becomes critical when diagnosing faults or ensuring safety. A conductor at high potential relative to ground must be insulated accordingly. Leakage currents flow between conductors at different potentials through the insulation; the voltage between them determines the leakage current magnitude given the insulation resistance. Electrostatic discharge, uncontrolled movement of charge between points at different potentials, can destroy semiconductor components, which is why controlled potential environments and grounding protocols are essential in electronics manufacturing.