Electric Field of a Point Charge Calculator
Calculate the electric field magnitude of a point charge using E = kQ/r². Free online physics calculator with Coulomb's constant, interactive charts, and detailed breakdown.
About This Calculator
The Electric Field of a Point Charge Calculator helps students, physicists, and engineers compute the magnitude of an electric field created by a single point charge at any given distance. Whether you're studying electrostatics, preparing for a physics exam, or working on an engineering project, this calculator provides instant, accurate results using the fundamental formula E = kQ / r².
The calculation uses Coulomb's constant (k = 8.9876 × 10⁹ N·m²/C²), derived from the permittivity of free space (ε₀). Enter the charge in coulombs and the distance in meters, and the calculator computes the electric field magnitude in newtons per coulomb (N/C). The result cards, interactive bar and pie charts, and detailed breakdown table help you visualize the relationship between charge, distance, and field strength.
The inverse-square relationship (E ∝ 1/r²) means the field strength drops dramatically with distance — a key concept in electrostatics. The calculator handles charges of any magnitude, from elementary particle charges (e = 1.602 × 10⁻¹⁹ C) to macroscopic charged objects. Results are displayed in scientific notation for precision, and you can share any calculation by copying the URL.
Frequently Asked Questions
What is the formula for the electric field of a point charge?
The electric field of a point charge is given by the formula E = kQ / r², where E is the electric field magnitude in N/C, k is Coulomb's constant (8.9876 × 10⁹ N·m²/C²), Q is the charge in coulombs, and r is the distance from the point charge in meters.
What is Coulomb's constant?
Coulomb's constant is k = 1/(4πε₀) ≈ 8.9876 × 10⁹ N·m²/C². It is derived from the permittivity of free space (ε₀) and relates the electric force between two point charges to the product of their charges and the inverse square of their distance.
Is the electric field a vector or scalar quantity?
The electric field intensity is a vector quantity. It requires both magnitude and direction for its complete description. The direction points radially outward from a positive point charge and radially inward toward a negative point charge.
How does the electric field change with distance?
The electric field varies as the inverse square of the distance from the point charge: E ∝ 1/r². This means doubling the distance reduces the field strength to one-quarter, and tripling reduces it to one-ninth.
What is the SI unit of electric field?
The SI unit of electric field is newtons per coulomb (N/C). It can also be expressed in volts per meter (V/m), which is equivalent: 1 N/C = 1 V/m.
Can this calculator handle very small charges like the elementary charge?
Yes, you can enter any charge value in coulombs, including the elementary charge e = 1.602 × 10⁻¹⁹ C. The calculator uses scientific notation for display, making it suitable for atomic-scale particle physics calculations.
Is this calculator free to use?
Yes, this electric field calculator is completely free to use with no registration required. Results can be shared via URL with all input parameters saved.