An electron is fired through a small hole in the positive plate of a parallel$-$plate capacitor at a speed of $1\mathrm{.}1$ x $10^7$ m$/$s $.$ The capacitor plates, which are in a vacuum chamber, are $2\mathrm{.}1-$cm $-$diameter disks spaced $3\mathrm{.}0$ mm apart. The electron travels $2\mathrm{.}5$ mm before being turned back.

What is the capacitor's charge?

Express your answer with the appropriate units.