The Capacitors calculator has equations for q=CV1 and to calculate the effective capacitance of capacitors in series2 or in parallel3.
In casual terms, capacitors store electric energy, kind of like a battery. Most batteries work through chemical potential energy, but capacitors instead store energy by putting opposite charges on two plates (a positive plate and a negative plate).
q = C ⋅ V
The voltage difference across a capacitor (V) is proportional to the amount of charge (q) on each plate of the capacitor. We write this relationship as q=CV, where where C is the "capacitance", and depends on the material and geometry of the capacitor.
The q=CV calculator tab has different variations of q=CV, just to help you with the math.
For an example of capacitors in series and a derivation of the following equation, please see this tutorial on electronics, specifically capacitors in series. We can describe the effective capacitance of capacitors in series with:
If there's more than two capacitor series, we can expand the equation like so:
For an example of capacitors in series and a derivation of the following equation, please see this tutorial on electronics, specifically capacitors in parallel. We can describe the effective capacitance of capacitors in parallel with:
That's for just two capacitors in parallel. For more i-many capacitors, we use: