1 \begin{problem*}{26.57}
2 A $2.00\U{nF}$ parallel-plate capacitor is charged to an initial
3 potential difference of $\Delta V_i=100\U{V}$ and is then isolated.
4 The dielectric material between the plates is mica, with a dielectric
5 constant of $5.00$. \Part{a} How much work is required to withdraw
6 the mica sheet? \Part{b} What is the potential difference across the
7 capacitor after the mica is withdrawn?