Gauss Law Calculator
Calculate electric flux, enclosed charge, or electric field using Gauss law for spherical, cylindrical, and planar symmetry.
What Is Gauss's Law?
Gauss's law relates the electric flux through a closed surface to the charge enclosed within it: Φ = Q / ε₀, where ε₀ = 8.854 × 10−12 F/m is the permittivity of free space. For a point charge inside a spherical Gaussian surface of radius r, the electric field magnitude is E = Q / (4πε₀r²).
Spherical Symmetry
When charge distribution has spherical symmetry, the field is radial and uniform over any concentric sphere. The flux integral simplifies to E × 4πr² = Q / ε₀. This lets you solve for electric field, enclosed charge, flux, or radius depending on what is known.
Key Relationships
- Electric flux: Φ = Q / ε₀ (total flux through any enclosing surface)
- Electric field: E = Q / (4πε₀r²) (at distance r from point charge)
- Enclosed charge: Q = Φ × ε₀
Frequently Asked Questions
Does the Gaussian surface shape matter?
Gauss's law holds for any closed surface. A sphere is chosen when the charge distribution has spherical symmetry, because the field is constant over the surface and the math simplifies.
What if the charge is outside the surface?
Charge outside the Gaussian surface contributes zero net flux. Only charge enclosed within the surface appears in Q.
What units does electric flux use?
Electric flux is measured in newton-meters squared per coulomb (N·m²/C), equivalent to volt-meters (V·m).
Can I use this for multiple point charges?
Yes. By superposition, add the enclosed charges algebraically (including sign) and use the total Q in Gauss's law.