Capacitance (A-level only) Flashcards – AQA A-level Physics (7408)

What is capacitance, and how is it expressed in terms of charge and potential difference?

Capacitance is charge stored per unit potential difference: $C = \frac{Q}{V}$ where $Q$ is the magnitude of charge on either plate and $V$ is the potential difference between the plates.

How do the charges on the two plates of a capacitor compare?

They are equal in magnitude and opposite in sign.

For a capacitor with constant capacitance, how does stored charge depend on potential difference?

Charge is directly proportional to potential difference: $Q = CV$.

What is the SI unit of capacitance, expressed in coulombs per volt?

The farad (F): $1\,\mathrm{F} = 1\,\mathrm{C}\,\mathrm{V}^{-1}$.