A parallel-plate capacitor has plate area and plate separation
PHYSICS · Subjective · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A parallel-plate capacitor has plate area 120cm2 and plate separation 2.0mm. It is connected to a 100V source while the region between the plates is filled with a dielectric material of relative permittivity 4.0.
(a) Calculate the capacitance of the capacitor with the dielectric in place.
(b) Determine the electrostatic energy stored while the capacitor is still connected to the source.
(c) The source is now disconnected and the dielectric slab is carefully removed without allowing any charge to leak. Calculate the new potential difference between the plates and the energy stored in this state.
(d) Find the percentage change in energy that occurred during the removal of the dielectric and explain briefly why this change takes place.