What is the difference between electric potential and electric field?

Electric field E = kQ/r² is a vector quantity (has direction). Electric potential V = kQ/r is a scalar quantity (just a number with a sign). Potential is related to the work needed to move a test charge from infinity to that point.

Why is potential zero at infinity?

The formula V = kQ/r approaches zero as r → ∞, which is the standard reference point. Potential is defined relative to infinity, so an isolated charge has zero potential infinitely far away.

Can electric potential be negative?

Yes. A negative source charge Q produces a negative potential at every surrounding point. This means positive test charges are attracted toward it (moving toward lower potential).

What units are used for electric potential?

Volts (V), also written as joules per coulomb (J/C). A potential of 1 V means 1 joule of work is done moving 1 coulomb of charge from infinity to that point.

Does this work for multiple charges?

This calculator handles one point charge at a time. For multiple charges, compute V = kQ/r for each and add the results algebraically (potentials are scalars, so no vector addition is needed).

Electric Potential Calculator

Name: Electric Potential Calculator
Availability: InStock
Author: Nham Vu

Enter a point charge and distance to compute the electric potential V = kQ/r in volts.

Inputs

V = kQ / r · k = 8.9875 × 10⁹ N·m²/C²

Point charge Q

Distance r

Result

Enter charge and distance, then click Calculate.

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Summary

Enter a point charge and distance to compute the electric potential V = kQ/r in volts.

How it works

Enter the point charge Q and choose its unit (C, µC, nC, or pC).
Enter the distance r from the charge to your point of interest and choose its unit.
The calculator uses Coulomb's constant k = 8.9875 × 10⁹ N·m²/C².
Electric potential is computed as V = kQ/r and displayed in volts.
Positive Q gives positive potential; negative Q gives negative potential.
The formula breakdown shows every substituted value so you can follow the math.

Use cases

Find the voltage at a point near a charged particle in physics problems.
Verify hand-calculated potentials on homework or exam prep.
Explore how potential scales with distance (inversely proportional to r).
Compare potential values for different charge magnitudes at the same distance.
Use as a building block when summing potentials from multiple charges (superposition).

Frequently Asked Questions

Last updated: 2026-06-10 · Reviewed by Nham Vu