The zap when you touch a doorknob on a dry winter day is an electric field discharging through you. An electric field is the invisible push that a charged object exerts on the space around it, measured in newtons per coulomb — the force each coulomb of charge would feel there. The force on any charge sitting in a field is simply charge times field strength: F = q × E. Double the charge, double the yank.

Fields also radiate from charges themselves: a point charge Q creates a field of kQ/r² at distance r, falling off with the square of the distance — which is why static cling is fierce up close and negligible across the room. Photocopiers and laser printers choreograph these fields to steer toner with exquisite precision, and the field between storm clouds and ground is what finally rips the air apart as lightning.

This calculator computes the force-on-a-charge product. Type the charge in coulombs in the Variable A box — static charges are tiny, like 0.000001 for a microcoulomb — and the field strength in newtons per coulomb in the Variable B box. The Result box gives the force in newtons. A microcoulomb in a 1,000 N/C field feels a millinewton — small, but plenty to lift a dust mote or snap a spark across a fingertip.

With the pre-filled defaults — Variable A 10, Variable B 5 — the Electric Field Calculator returns Result 50.0000. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.