hello every body, I am trying to understand the capacitor behavior as deeply as i can ...I posted this thread in Classical Physics section but I later think it could be better if I post it here in EE. consider a simple capacitor with two plates A and B ---| |--- 1- why the charge on both plates are equal in magnitude ? when we apply a voltage to a capacitor,charge will accumulate on side A.this charge will build an E field which will pass thru the insulator and exert force on the plate B.So charges on plate B move and accumulate together.Ok but how do we know that this E field caused by Charges on plate A will exactly attract the same amount of charge that was on plate A on plate B?? why these two has to be equal ? Conservation of Charge Law ? 2 - why is that the higher the frequency , the more is the current ? is the following intuition wrong ? when we apply a ac voltage to plate A of a capacitor , charges density on plate A will change with voltage. when charge density changes , E field caused by them in the Capacitor changes too. This changing E filed will cause the plate B charge density changing . Ok but I am thinking that when the E filed is changing very fast(high freq.) the plate B charges may not find enough time to respond to it and move to the new configuration.so the charge density(voltage) on plate B may lag the charge density(voltage) of plate A. Isnt this in contradiction to that at high freq. the capacitors impedance is lower ?