Permittivity constant
\[ \epsilon_0 = 8.85 \times 10^{-12} \si{F.m^{-1}} = 8.85 \si{pF.m^{-1}} \]
Capacitance
\[ q = CV \]
easured in Farad, C/V How much charge must be put on the plates to produce a certain p.d. between them
Finding C based on geometrical factors
\[ C = \frac{\epsilon_0 A}{d} \]
Capacitors in circuits
In series:
\[ \frac{1}{C_{eq}} = \sum_i \frac{1}{C_i} \]
Same Q, all V_i add to total p.d.
In parallel:
\[ C_{eq} = \sum_i \frac{1}{C_i} \] Same V, all Q_i add to Q