Capacitance (C = Q/V)
Worked example: 1 mC at 10 V → 100 uF — press Try an example to run it live, then adjust anything.
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Grade 12Grade 12 Physics
Capacitance →
UniversityCircuits & Electrical Power
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Capacitance (C = Q/V) explained
Capacitance is charge-storing capacity: how many coulombs a capacitor soaks up for every volt you apply across it. The unit, the farad, honors Michael Faraday — and it is a giant. A full farad would have been a bench-filling curiosity for most of electronics history, so practical parts are marked in microfarads, nanofarads, and picofarads; only modern supercapacitors reach whole farads. Doubling the applied voltage doubles the stored charge, but C itself stays fixed — it depends only on geometry and the insulating material between the plates.
Worked example: a 100 µF capacitor charged to 12 V holds Q = CV = 100×10⁻⁶ × 12 = 1.2 mC of charge — about 7.5×10¹⁵ electrons parked on one plate and missing from the other. This defining relation applies to every capacitor, from the tuning capacitor in a radio to the DRAM cell storing one bit in your computer.
Capacitance (C = Q/V) formula
- = Capacitance (μF)
- = Charge (C)
- = Voltage (V)
Missing one of these? Work it out first, then come back
- Capacitance — RC Time Constant, Energy Stored in a Capacitor
- Charge — Electric Charge (Q = It), Coulomb's Law
- Voltage — Ohm's Law, Electrical Power (P = VI)