Coulomb's Law Calculator

Category: Physics
- August 22, 2025
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Coulomb's Law describes the electrostatic force between two charged particles. This fundamental principle of electrostatics states that the force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.

This calculator allows you to determine the electrostatic force, electric field, and potential energy between charged particles using Coulomb's Law.

What would you like to calculate?

C
? The magnitude of the first charge in Coulombs (C). For example, an electron has a charge of -1.602 × 10⁻¹⁹ C.
C
? The magnitude of the second charge in Coulombs (C).
? The distance between the centres of the two charges.

Display Options

? Include the effect of a dielectric medium between the charges. This will reduce the electrostatic force by a factor of the dielectric constant.

About Coulomb's Law

Coulomb's Law, formulated by French physicist Charles-Augustin de Coulomb in 1785, describes the electrostatic force between two electrically charged particles. It is a fundamental principle in electrostatics.

The Mathematical Expression:

Coulomb's Law is mathematically expressed as:

F = k × (|q₁ × q₂|) / r²

Where:

  • F is the electrostatic force between the charges (in Newtons, N)
  • k is Coulomb's constant (8.9875 × 10⁹ N·m²/C²)
  • q₁ and q₂ are the magnitudes of the charges (in Coulombs, C)
  • r is the distance between the centres of the charges (in metres, m)
Related Electric Field Equations:

The electric field at a distance r from a point charge q is given by:

E = k × |q| / r²

The electric potential at a distance r from a point charge q is given by:

V = k × q / r

The electric potential energy of two point charges q₁ and q₂ separated by a distance r is given by:

U = k × q₁ × q₂ / r
Effect of Dielectric Media:

When charges are in a medium other than vacuum, the electrostatic force is reduced by a factor equal to the dielectric constant (ε) of the medium:

F = k × (|q₁ × q₂|) / (ε × r²)

The dielectric constant is a measure of the medium's ability to "store" electric field energy. The higher the dielectric constant, the more the medium weakens the electric field.

Medium Dielectric Constant (ε)
Vacuum 1.0 (exact)
Air (at STP) 1.00059
Water 80
Glass 5-10
Plastic 2-4
Paper 3.7
Oil 2.4
Key Applications:
  • Atomic and Molecular Structure: Coulomb's Law explains the attractive force between electrons and the nucleus in atoms.
  • Electrical Engineering: Used in designing capacitors, insulators, and other electrical components.
  • Chemical Bonding: Ionic bonds and electrostatic interactions in molecules are described by Coulomb's Law.
  • Electrostatic Precipitators: Used to remove particles from a gas stream by applying an electric charge.
  • Lightning: The buildup and discharge of electric charge in clouds can be explained using Coulomb's Law.
  • Biological Processes: Many biological processes involve electrostatic interactions between charged molecules.

Understanding Coulomb's Law

Coulomb's Law is a key concept in Physics that explains how charged particles interact. It tells us that the electric force between two charges is directly linked to the size of the charges and inversely linked to how far apart they are. This means that the closer the charges are, the stronger the force between them. This calculator uses Coulomb's Law to help you calculate important electrostatic properties between these charges.

What Can You Calculate with the Coulomb's Law Calculator?

This handy calculator allows you to find various electrostatic properties. You can calculate:

  • Electrostatic Force between two charged particles
  • Electric Field strength created by a charge
  • Electric Potential at a point in space
  • Potential Energy associated with two charges

Each calculation helps you understand the behaviour of charged particles better.

Easy Input for Charge and Distance

Using the Coulomb's Law Calculator is simple. Just input the two charges and the distance between them. You can enter the values in different units, like Coulombs for charge and metres or centimetres for distance. This flexibility makes it easy to work with the specific values you have in mind.

Choosing the Type of Calculation

When you open the calculator, you see options for what you'd like to calculate. You can choose to calculate the electrostatic force, electric field, electric potential, or potential energy. Depending on your choice, the calculator will show the relevant input fields, guiding you through the process smoothly.

Understanding Common Charge Values

The calculator also provides preset common charge values. This is helpful if you want to use standard values like those for an electron or a proton. You can select these presets to avoid entering values manually each time, making calculations faster and easier.

Advanced Options for Precision

If you need more control over your results, the calculator includes advanced options. You can set the number of decimal places for your answers or choose between standard and scientific notation. Additionally, you can factor in the impact of different dielectric materials if needed, which alters how charges interact in various media.

Visualising Your Results

Once you've made your calculations, the results are displayed clearly. You get the primary outcome, such as the electrostatic force, along with the direction of the force, and Other related values. The calculator also features a diagram to visually represent the forces involved, helping you grasp the interactions between charged particles better.

Applications of Coulomb's Law in Everyday Life

Coulomb's Law is more than just theory. It's used in many real-world applications, including:

  • Understanding atomic structure and chemical bonding
  • Designing electrical components like capacitors
  • Explaining lightning and electrostatic phenomena
  • Handling electrostatic interactions in biological processes

This calculator not only helps you understand the law but also shows its relevance in daily life. Whether you're studying physics or working in engineering, this tool is valuable for grasping how electric charges operate in our world.