Analyze electrostatic energy using clear units and inputs. Review force, sign, dielectric effects, and meaning. Built for students, labs, simulations, reports, and careful comparisons.
| Case | Charge 1 | Charge 2 | Distance | Dielectric Constant | Energy (J) | Force (N) | Type |
|---|---|---|---|---|---|---|---|
| Vacuum Pair | 1 uC | -1 uC | 5 cm | 1 | -1.797510e-1 | 3.595021e+0 | Attractive |
| Water Screened Pair | 2 nC | -3 nC | 2 nm | 78.5 | -3.434733e-1 | 1.717367e+8 | Attractive |
| Air Like Charges | 5 uC | 5 uC | 12 cm | 1.0006 | 1.871284e+0 | 1.559403e+1 | Repulsive |
| Protein Interior | 50 pC | -80 pC | 4 nm | 4 | -2.246888e-3 | 5.617220e+5 | Attractive |
Electrostatic interaction energy: U = (k × q1 × q2) / (εr × r)
Force magnitude: F = (k × |q1 × q2|) / (εr × r²)
Electric potential from charge 1 at distance r: V = (k × q1) / (εr × r)
Coulomb constant: k ≈ 8.9875517923 × 109 N·m²/C²
The sign of energy matters. Positive energy usually means repulsion. Negative energy usually means attraction. Larger distance lowers energy magnitude. A larger dielectric constant also weakens the interaction.
Electrostatic interaction energy describes the work linked to two charges at a given separation. It helps explain attraction, repulsion, and stability. A negative value often shows a favorable attraction. A positive value often shows resistance between like charges. This idea appears in chemistry, condensed matter physics, nanoscience, and molecular modeling.
The energy follows an inverse distance relationship. When two charges move closer, the magnitude of interaction energy rises quickly. Small distance changes can create large energy shifts. This matters in ionic pairs, colloids, proteins, host guest systems, and charged surfaces. Accurate distance input improves realism and reduces interpretation errors.
The surrounding medium changes the dielectric constant. A higher dielectric constant reduces electrostatic interaction. Water is a classic example. It screens charges strongly. Vacuum and air screen weakly. This difference is critical in solvent studies, membrane systems, and biochemical environments. The same charges can behave very differently in different media.
This calculator returns energy in joules and electronvolts. It also reports force magnitude and electric potential. Joules help with larger engineering or laboratory values. Electronvolts help with atomic and molecular scale interpretation. The interaction label tells you whether the pair is attractive or repulsive. These outputs support faster checks and better communication.
Students can use it for homework, reports, and concept review. Researchers can use it for quick screening before deeper simulation. Engineers can use it for sensor spacing, dielectric comparisons, and design checks. It is also useful when comparing media, unit scales, and charge signs. Clear unit conversion helps avoid mistakes. Reliable interpretation helps turn raw numbers into useful decisions.
A negative value usually means the charges attract each other. The pair is energetically favorable at that separation. Opposite charges commonly produce this result.
A positive value usually means the charges repel each other. Like charges create this pattern. More work is needed to push them together.
Water has a high dielectric constant. That strong screening lowers the effective Coulomb constant. As a result, both energy magnitude and force magnitude become much smaller.
Yes. The calculator converts common charge and distance units into SI values first. That makes it useful for nanoscale, molecular, and materials calculations.
It is most accurate for point charges or center to center approximations. Extended shapes, distributed charge clouds, and complex geometries need more advanced models.
Force describes the instantaneous push or pull between charges. Energy describes the work associated with their separation. They are related, but they answer different questions.
Electronvolts are convenient for atomic and molecular scales. They make tiny energy values easier to compare in chemistry, spectroscopy, materials science, and simulation work.
If one charge is zero, the interaction energy and force both become zero in this model. No electrostatic pair interaction remains between the two entries.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.