A 2.00-nF parallel-plate capacitor is charged to an initial potential difference Vi = 100 V and then

Question:

A 2.00-nF parallel-plate capacitor is charged to an initial potential difference ∆Vi = 100 V and then isolated. The dielectric material between the plates is mica, with a dielectric constant of 5.00.
(a) How much work is required to withdraw the mica sheet?
(b) What is the potential difference of the capacitor after the mica is withdrawn?