MotionLab

Electric Field Calculator

The invisible force field that a charge creates in the space around it.

Point charge (C)

Distance (m)

Electric field (N/C)

35,950.207

E = kq/r², V = kq/r

Electric potential (V): 17,975.104

What you entered

Point charge (C): 0.000001Distance (m): 0.5

1
E = k|q| ÷ r²
8.988e+9 × |1.00e-6| ÷ 0.5²= 3.5950e+4 N/C
2
V = kq ÷ r
8.988e+9 × 1.00e-6 ÷ 0.5= 17975.1036 V

Result

Electric field (N/C): 35,950.207

A charge of 1.00e-6 C creates a field of 3.5950e+4 N/C and potential of 17,975.104 V at 0.5 m.

Electric field and potential from a point charge

Field strength falls with the square of distance while potential falls only linearly, which is why the two columns diverge.

Charge (C)	Distance (m)	Field (N/C)	Potential (V)
1e-9	0.01	8.9876e+4	8.9876e+2
1e-6	0.1	8.9876e+5	8.9876e+4
1e-6	1	8.9876e+3	8.9876e+3
1e-3	0.5	3.5950e+7	1.7975e+7
1.6e-19	1e-10	1.4380e+11	1.4380e+1

Rows two and three are the same charge at 0.1 m and 1 m: the field drops by a factor of 100 while the potential drops by only 10, because field goes as one over r squared and potential as one over r. At exactly 1 m the two happen to share a numerical value, which is a coincidence of units rather than physics. The last row is a single proton at atomic distance, producing an enormous field of 1.4e11 N/C - fields inside atoms dwarf anything achievable in a laboratory. Air breaks down and sparks at around 3e6 N/C.

Field vs. potential — force vs. energy

The electric field (E = kq/r²) tells you the force per unit charge at a point — it's a vector pointing away from positive charges and toward negative ones. The electric potential (V = kq/r) tells you the potential energy per unit charge — it's a scalar that drops off more slowly (1/r vs. 1/r²).

Superposition builds complex fields from simple ones

Real charge distributions create complicated field patterns, but every such field is just the sum (superposition) of simple point-charge fields — this calculator gives you the building block that all electrostatics is assembled from.

Frequently asked questions

A +1 μC charge sits 0.5 m away. What's the electric field at my location?

E = kq/r² = 8.99×10⁹ × 10⁻⁶ / 0.25 = 35,960 N/C ≈ 36 kN/C. The field points away from the positive charge (toward you if you're farther away). Potential: V = kq/r = 8.99×10⁹ × 10⁻⁶ / 0.5 = 17,980 V.

How strong is the electric field that causes air to break down (lightning)?

Air breaks down at about 3 MV/m (3 million V/m). A thundercloud at 5 km altitude with 100 MV potential difference creates E ≈ 20 kV/m on average, but local field enhancement at pointed objects (lightning rods, treetops) can reach breakdown levels and trigger a strike.

What's the difference between electric field and electric potential?

Electric field (E = kq/r²) is force per charge — a vector that points in the direction a positive charge would accelerate. Potential (V = kq/r) is energy per charge — a scalar measuring stored energy. Field drops as 1/r², potential as 1/r. See Coulomb's law calculator for the force itself.

How do I find the field from multiple charges?

Use superposition: calculate the electric field from each charge separately, then add the vectors. Two equal positive charges side by side create a field that points away from both, with a zero point exactly between them. This calculator handles single point charges — the building block for all configurations.

Is the electric field inside a conductor zero?

Yes — in electrostatic equilibrium, the field inside a conductor is exactly zero. Free electrons redistribute until they cancel any internal field. All excess charge sits on the surface. This is why Faraday cages work — the metal shell screens out external electric fields completely.