Electrostatic potential
What is electric potential?
Electric potential describes the electric potential energy available per unit charge at a particular location in an electric field.
For a single stationary point charge, electric potential depends on the source-charge magnitude and the distance from that charge.
Main equation
Electric potential formula
Electric potentialV = kQ ÷ r
- V is electric potential in volts.
- Q is source-charge magnitude in coulombs.
- r is distance from the point charge in metres.
- kis Coulomb's constant.
Rearranged equations
Solve for charge or distance
Source charge
Q = Vr ÷ k
Multiply potential by distance, then divide by Coulomb's constant.
Distance
r = kQ ÷ V
Multiply Coulomb's constant by charge, then divide by potential.
Worked example
Calculate electric potential
- Source charge is 2 × 10⁻⁶ C.
- Distance is 0.05 m.
- Apply V = kQ ÷ r.
- Substitute the known values into the equation.
- Electric potential is approximately 359,502 V.
Related concept
Potential versus potential energy
Electric potential is measured in volts and represents energy per unit charge.
Electric potential energy is measured in joules and depends on the charge placed at that potential. The two concepts are related by U = qV.
Potential sign
Positive and negative source charges
A positive source charge produces positive electric potential, while a negative source charge produces negative electric potential.
This calculator uses positive charge and potential magnitudes. Apply the appropriate sign separately based on the source charge.
Unit guidance
Electric potential units
- Electric potential: volts (V).
- Source charge: coulombs (C).
- Distance: metres (m).
- 1 microcoulomb = 1 × 10⁻⁶ C.
- 1 nanocoulomb = 1 × 10⁻⁹ C.
Model limitations
Assumptions and limitations
The point-charge equation assumes a stationary source charge in vacuum or approximately in air. Distance is measured from the centre of the charge.
Multiple charges, extended charge distributions, conductive surfaces, dielectric materials, and complex geometries require superposition or more advanced electrostatic models.
Related tools
Continue your electrostatics analysis
Use the Electric Field Calculator to calculate field strength, force, charge, or distance.
Use the Coulomb's Law Calculator to calculate electrostatic force between two point charges.
Questions and answers
Electric potential calculator FAQ
What formula does the electric potential calculator use?
The calculator uses V = kQ/r, where V is electric potential, Q is source-charge magnitude, r is distance, and k is Coulomb's constant.
What is the unit of electric potential?
Electric potential is measured in volts. One volt equals one joule per coulomb.
How do I calculate the source charge?
Multiply electric potential by distance and divide by Coulomb's constant using Q = Vr/k.
How do I calculate distance from a point charge?
Multiply Coulomb's constant by the source charge and divide by electric potential using r = kQ/V.
Is electric potential the same as electric potential energy?
No. Electric potential is energy per unit charge, while electric potential energy depends on both the potential and the charge placed in the field.