Electric Charge
What electric charge is, the size of the elementary charge, how coulombs relate to amp-hours, and why battery capacity is quoted in mAh.
Questions people ask
Why compare two batteries by watt-hours rather than mAh?
Because mAh ignores voltage. A 3000 mAh cell at 3.7 V holds 11.1 Wh; the same mAh at 1.2 V holds only 3.6 Wh. Watt-hours is the fair comparison.
What is the smallest possible charge?
For anything you can isolate, the elementary charge of 1.602 × 10⁻¹⁹ C. Quarks carry thirds of it but are never found alone.
Does this page work offline?
Yes, after the first visit. The service worker caches it, so the reference stays available with no connection.
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Last updated 22 August 2026