How this calculator works
A stationary point charge creates a radial inverse-square electric field. The sign of the radial result indicates outward or inward direction. For several sources, electric fields add as vectors, not as unsigned magnitudes. System mode uses the displacement from each source to the observation point to resolve the components. All sources are assumed embedded in the same uniform linear dielectric.
Formula
Single source: Er = kq/(epsilonr r²). Vector sum: E = (k/epsilonr) sum(q_i (r-r_i)/|r-r_i|³), with k = 1/(4 pi epsilon0).
Worked example
A +1 microcoulomb source at 1 m produces +8987.55 V/m in vacuum. A -4 microcoulomb source at 2 m in a dielectric with epsilonr = 2 produces -4493.78 V/m.
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Frequently asked questions
Is V/m the same as N/C?
Yes. Both express electric field in equivalent SI units.
Can fields cancel?
Yes. Vector components may cancel even when individual field magnitudes are large.
Why is a coincident point rejected?
An ideal point source has a singular field at its own position. A finite charge distribution needs integration.