Capacitor V-I CharecteristicsWatch
This part was definitely covered at A-Level (right at the start when discussing the basics of capacitors, at least in AQA. Idk about OCR or the others, but I would expect it to be so.)
The next part is just working backwards, and is just an integral...
where you'd throw in some boundary conditions, etc, to retrieve and .
Capacitance has been assumed constant here, which for all purposes is what you should assume for any component.