Free · Electromagnetism calculators 🧲

Charge, Voltage & Electric Potential Energy

Convert charge and electric potential difference into signed potential-energy change, in electron-volts or joules.

  • Formula & worked example
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

A charge of +2 elementary charges crossing a +12 V potential difference has a potential-energy change of +24 eV.

ΔU = qΔV

Worked example

Enter these known values and leave the other values blank.

Electric potential difference ΔV
12 V
Signed electric charge q
2 e
Potential-energy change ΔU
24 eV

Assumptions and limitations

  • Signs matter: q and ΔV may be positive, negative or zero. This output is potential-energy change; work done by the electric field is −ΔU.
  • One elementary charge is exactly 1.602176634 × 10⁻¹⁹ C, and one eV is exactly that many joules.
  • A zero product does not uniquely determine a missing charge or voltage when the other factor is zero.

Common questions

Does an electron always gain the displayed energy?

No. An electron has negative charge. Its kinetic-energy change depends on field work and other forces; this calculator returns signed potential-energy change.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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