Practical tools for measured work
Electric field, force and potential calculator
Calculate signed point-charge field, force, potential and energy, or a uniform field from voltage drop.
Calculate the layout, check the diagram, then print the result for the shop or jobsite.
How it works
For a point charge Q, E = kQ/r² and V = kQ/r, with potential zero at infinity. Force on test charge q is qE and potential energy is qV. Positive radial direction points away from the source; a negative force is attraction. k = 1/(4πε0εr), using ε0 = 8.8541878188 × 10⁻¹² F/m. A uniform field uses the potential drop along a direction divided by separation.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Electric field model
- Isolated point charge
- Signed test charge
- -2 µC
- Signed source charge
- 1 µC
- Distance from source charge
- 0.1 m
- Relative permittivity
- 1
Primary result: Signed radial electric field: 898755.1786 N/C.
Before using the result
- Check the selected mode, units and input values before using the result.
- Read the assumptions and rounding rules; compare the worked example with your intended calculation.
- A numerical result does not supply missing context or change the stated limitations.
Limitations
The point-charge model assumes a homogeneous linear dielectric and an isolated source; it does not model conducting boundaries or multiple-charge geometry. Relative permittivity must be at least one. Uniform-field mode ignores edge effects and uses the stated voltage-drop direction.
Frequently asked questions
What should I verify before using this result?
Check the input values, units, dates and assumptions. Compare the method and its stated limits with the source relevant to your task.
Why might the finished result differ?
Results depend on the entered data and the model’s assumptions. Rounding, changing conditions or omitted factors can affect the comparison. Read the limitations before using the result.
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