A capacitor has some dielectric between its plates, and the capacitor is connected to a DC source. The battery is now disconnected and then the dielectric is removed. State whether the capacitance, the energy stored in it, electric field, charge stored and the voltage will increase, decrease or remain constant.

Question

Philoid · Accepted Answer

• The capacitance of the parallel plate capacitor filled with dielectric medium of dielectric constant k is given by

where K = dielectric constant

A = Area of parallel plate

d = diameter of parallel plate

• capacitance of parallel plate capacitor decreases when k =1 for air medium and for dielectric K > 1

• if we disconnect the battery from capacitor then the charge stored will remains the same due to conservation of charge

• the energy stored in an isolated charge capacitor

Where q= constant

• the energy stored As C decreases with removal of dielectric medium therefore energy stored increases

• the potential across the plate of the capacitor is given by since q is constant, C is decreases which is then increases V and E is increases as