Calculate electric field strength from a point charge
Charge q (C)
Distance r (m)
Result
Answer
Step-by-Step Derivation
Electric Field Formula
E = k |q| / r^2
k = 8.9875517923 x 10^9 N m^2/C^2
The electric field of a point charge gives force per unit charge at a location. It decreases with the square of distance from the charge.
⚠This formula assumes a point charge in vacuum or air approximation. Nearby conductors, dielectrics, and multiple charges change the field.
What Is Electric Field Strength?
Electric field strength describes how strongly a charge would push or pull another charge at a point in space. It is measured in newtons per coulomb or volts per meter.
Force Per Charge
E equals force divided by test charge.
Point Charge
The formula models charge concentrated at one point.
Inverse Square
Field decreases rapidly with distance.
Direction Matters
Positive charges point outward; negative charges inward.
Example: For q = 1 microcoulomb and r = 0.5 m, E is about 35,950 N/C.
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