Calculator
Example Data Table
| Charge 1 | Charge 2 | Distance | Relative Permittivity | Force Magnitude | Behavior |
|---|---|---|---|---|---|
| 5 µC | -3 µC | 20 cm | 1 | 3.370332 N | Attractive |
| 2 µC | 2 µC | 10 cm | 1 | 3.595021 N | Repulsive |
| 10 nC | -25 nC | 5 cm | 2.25 | 0.000399 N | Attractive |
| 1 mC | 0.5 mC | 2 m | 80 | 14.043050 N | Repulsive |
Formula Used
The calculator uses Coulomb law to estimate the force magnitude between two point charges.
F = k × |q1 × q2| ÷ (εr × r²)
Here, F is electric force in newtons. The values q1 and q2 are charges in coulombs. The value r is the distance in meters. The value k is 8.9875517923 × 10⁹ N·m²/C². The value εr is relative permittivity. Use εr = 1 for air or vacuum approximations.
The calculator also reports electric field strength and potential energy. Electric field values help compare how strongly each charge affects space around the other charge. Potential energy keeps the sign of the charge product, so it can show attractive or repulsive energy behavior.
How to Use This Calculator
- Enter the first charge value and choose its unit.
- Enter the second charge value and choose its unit.
- Enter the distance between both charges.
- Select the distance unit used in your measurement.
- Enter relative permittivity for the medium.
- Choose decimal places for the final output.
- Press the calculate button to view the result above the form.
- Use the CSV or PDF button to save your result.
Electrical Force Analysis Guide
Why Electric Force Magnitude Matters
Electric force is a basic idea in electrical science. It explains how charged objects pull or push each other. A small charge can create a large force when the distance is short. This is why spacing matters in sensors, capacitors, electrostatic devices, and laboratory demonstrations. The calculator helps convert common charge units before applying Coulomb law. This reduces mistakes caused by micro, nano, or milli prefixes.
Understanding Charge Signs
The force magnitude is always positive. It describes strength only. Direction depends on signs. Like charges repel each other. Opposite charges attract each other. The tool checks signs and gives a simple interaction note. This makes the result easier to use in homework, circuit theory, and field studies. A zero charge gives zero mutual force, because both charges must exist for interaction.
Distance and Medium Effects
Distance has a squared effect. Doubling distance reduces force to one fourth. Halving distance increases force four times. The medium also matters. Relative permittivity reduces force when charges are placed in insulating materials. Air is often close to one. Water, glass, oil, and plastics may need larger values. This option makes the calculator useful beyond ideal vacuum problems.
Advanced Output Uses
The result includes effective constant, electric field estimates, and signed potential energy. These values support deeper analysis. Electric field helps show charge influence at a point. Potential energy helps compare stable and unstable charge arrangements. The CSV export is useful for lab reports. The PDF export is useful for saving a clear calculation record. Use measured values carefully, because real objects are not always perfect point charges.
FAQs
What does electric force magnitude mean?
It means the strength of force between two charges. It does not show direction. Direction depends on whether the charges attract or repel.
Which law does this calculator use?
It uses Coulomb law. The formula relates charge size, distance, Coulomb constant, and relative permittivity.
Can I enter negative charges?
Yes. Negative values are allowed. The magnitude stays positive, while the calculator explains whether the interaction is attractive or repulsive.
What value should I use for relative permittivity?
Use 1 for air or vacuum approximation. Use a material-specific dielectric value when charges are inside another medium.
Why does distance affect force so strongly?
Coulomb law uses distance squared. A small distance change can create a large change in force magnitude.
What unit is used for the final force?
The main result is shown in newtons. The calculator also gives millinewtons and micronewtons for easier comparison.
Can this calculator handle very small charges?
Yes. It supports coulombs, millicoulombs, microcoulombs, nanocoulombs, and picocoulombs through automatic unit conversion.
Is this suitable for real objects?
It is best for point-charge models. Real objects may need geometry, charge distribution, shielding, and environmental corrections.