Re: capacitor
capacitor is an electrical device which can store energy. it stores energy in an electrical field unlike to an inductor which stores energy in a magnetic field. capacitor consists of a pair of metal plates separated by a dielectric material. initially when no potential has been apllied to the plates there is no field in the dielectric material and molecules are randomly oriented. when we apply a potential to the two plates of the capacitor, the dielectric material gets polarized, means the randomly arranged molecules get aligned in the direction of the field. theoritically it takes infinite time to align all the molecules in the direction of the field but practically nearly after five time constants the dielectric material gets polarized completely. so the capacitor gets fully charged. during the period of charging actually there is no current flow through the dielectric material. there is flow of current in the external circuitry but not in the dielectric material. this current is otherwise none as displacement cuurent. after the capacitor gets charged, if you suddenly cut the potential applied to the two plates, the capacitor still remains in the charged condition, because its dilectric material is still polarized.
to dissipate the charge you have to connect the two plates through a resistor, so that now current can flow in the opposite direction as compared to the initial charging current. but now also while discharging there is actually no flow of current through the dielectric material.