ONLINE ELECTRICAL ENGINEERING STUDY SITE

Voltage or Electric Potential Difference

Before understanding voltage or electric potential difference we should fist investigate how a charged particle moves in uniform static electric field.

Voltage Theory

Let us consider two parallel plates, that are connected to a battery. The upper plate is connected with positive terminal of a battery. Hence this plate is positively charged, and the lower plate is connected to negative terminal of the battery and hence this lower plate is negatively charged. These plates produce a static electric field between them which is proportional to surface charge density of both plates, let's the surface charge density of the upper plate is σ. Then surface charge density of lower plate will be - σ. The electric field produced by only positive plate is surface charge density divided by twice of permeability of the space between the plates i.e.

 Similarly static electric field produced by only negative plate is  Hence resultant electric field between the plates is  Let us now assume a positively charged particle enters into that electric field. If the particle has a charge of q Coulomb, then electrostatic force applied on that particle will be

Fe = q.E
Where, E is the electric field vector and it is constant for a uniform electric field. Now acceleration of the particle,  Where, m is the mass of the particle. Hence velocity of the particle at any instant t can be written as,  Where, vo is the initial velocity of the particle at entrance into uniform electric field.  So, position of the particle at any instant t can be written as,  Where, po is the initial position of the particle at entrance into uniform electric field.  This is a function of parabola, hence it can be predicted from the function that the motion of charged particle in an uniform electric field is projectile motion in parabolic path.

Electrical Potential Difference and Definition of Voltage

We can use electric field vector to characterize static electric field in a space. By observing the movement of charge particles inside an electric field, one can predict the exact characteristics of that field. If the field is strong enough, the deflection of charged particle in parabolic path will be more sharp and if the field is weak, deflection is less. But it is not the practical way of measuring the intensity of an electric field. Another physical quantity is there which is much easier to measure and also used to characterize an electric field and this quantity is known as electric potential difference. Uniform Electric Field Electrical potential V(t) of a position in the electrical field is such that, electric potential energy is required to place a particle of charge q at that position, would be the product of charge of the particle q and the potential of that position V(t). That is potential energy U(t) = q.V(t). The SI unit of electrical potential is Volt after name of Italian physicist Alessandro Volta (1745 - 1827). Voltmeter is used to measure the potential difference between two points. There is a misconception about potential and voltage. Many of us think that both are the same. But voltage is not exactly potential, it is the measure of electric potential difference of two points.

Electrical Potential and Electrical Field Vector

Electrical potential and electrical field vector, both characterize the same thing that is space of electrical field. Since both electric potential and electrical field vector describe an electric field, they are related. dV = - E.ds where dV is the potential difference between two points separated by a distance ds and electrical field vector is E.

Definition of Potential Difference or Voltage

After going through the above portion of voltage theory we can now establish a definition of potential difference, definition of voltage in few words. Which says
Voltage is the difference in electric potential energy per unit charge between two points. Voltage is the work to be done, upon an unit charge to move between two points, against a static electric field. A voltage which is a measure of electric potential difference, is the cause of electrical current to flow in a closed circuit.

Closely Related Articles Voltage in SeriesVoltage in ParallelVoltage Drop CalculationVoltage DividerVoltage MultiplierVoltage DoublerVoltage RegulatorVoltage FollowerVoltage Regulator 7805Voltage to Current ConverterMore Related Articles What is Capacitor and Capacitance? Types of CapacitorsWorking Principle of a CapacitorEnergy Stored in CapacitorQuality Factor of Inductor and CapacitorTransient Behavior of CapacitorCylindrical CapacitorSpherical CapacitorCapacitors in Series and ParallelTesting of Capacitor BankHow to Test Capacitors?Electric Circuit and Electrical Circuit ElementsSeries Parallel Battery CellsElectrical DC Series and Parallel CircuitRL Series CircuitRLC CircuitThree Phase Circuit | Star and Delta SystemRL Parallel CircuitRL Circuit Transfer Function Time Constant RL Circuit as FilterConstruction of AC Circuits and Working of AC CircuitsSeries RLC CircuitParallel RLC CircuitResistances in Series and Resistances in ParallelResonance in Series RLC CircuitPlanar and Non Planar Graphs of CircuitClipping CircuitElectrical Conductance Conductivity of Metal Semiconductor and Insulator | Band TheoryProperties of Electric ConductorElectrical Resistance and Laws of ResistanceSeries ResistanceEarn with usElectric Current and Theory of Electricity | Heating and Magnetic EffectNature of ElectricityDrift Velocity Drift Current and Electron MobilityElectric Current and Voltage Division RuleRMS or Root Mean Square Value of AC SignalWhat is Electric Field?Electric Field Strength or Electric Field IntensityStatic Electric Field | Electrostatic Induction What is Flux? Types of Flux?Magnetic PermeabilityMagnetic Field and Magnetic Circuit | Magnetic MaterialsMagnetic SaturationEnergy Stored in a Magnetic FieldHysteresis LoopA Current Carrying Conductor Within A Magnetic FieldMagnetic SusceptibilityHard Magnetic MaterialsSoft Magnetic MaterialsMagnetic Circuit with Air GapFourier Series and Fourier TransformTrigonometric Fourier SeriesAnalysis of Exponential Fourier SeriesElectrical and Electronics Engineering BooksWhat is Inductor and Inductance | Theory of InductorMutual InductanceSelf InductanceSI System of UnitsElectrical International SymbolElectric Power Single and Three Phase Power Active Reactive ApparentVector Algebra | Vector DiagramRelationship of Line and Phase Voltages and Currents in a Star Connected SystemVector Diagram | Three Phase Vector DiagramTypes of resistor Carbon Composition and Wire Wound ResistorVaristor Metal Oxide Varistor is nonlinear ResistorCarbon Composition ResistorWire Wound ResistorVariable Resistors | Defination, Uses and Types of Variable ResistorsLight Dependent Resistor | LDR and Working Principle of LDRSource of Electrical EnergyVoltage SourceIdeal Dependent Independent Voltage Current SourceNew Articles Electrical and Electronics Engineering BooksWater MeterAir MeterDigital PotentiometersBasic Construction of Wind Turbine