Determine the surface area $S$ of the plates of a parallel-plate capacitor, knowing that the distance between the plates is $d$ and that, when inserted into an RC circuit in series with a resistor of known resistance $R$, it charges exponentially with a time constant $\tau$. (Data: $R = 1 \, \text{k}\Omega; \, \tau = 0.01 \, \text{ms}; \, d = 4 \, \text{mm}
; k = \frac{1}{4 \pi \varepsilon_0} = 8.99 \times 10^9 \, \text{Nm}^2/\text{C}^2)$