If voltage is analogous to pressure and current to the flow of air, then you move your diaphragm to suck in some air through your mouth, the movement of your diaphragm is like an increase in voltage (pressure) which causes air to rush in. Once the lungs are filled, the air stops moving.
i=C*dv/dt means, the magnitude of current flow is directly proportional to the rate of change of the volts over time. Current flowing into a capacitor will cause the voltage to change, because more charge accumulated on the plates thus causing a greater voltage (i.e. pressure due to the imbalance of charge between the plates and the electrostatic attraction of the imbalance). And, if a current path is provided between the plates, a current will flow which will begin to balance out that charge difference and will gradually reduce the voltage at a certain rate of change.
bq). why is that current flows through capacitor only when voltage changes?
Current doesn't flow through the capacitor (not when it is functioning normally). It can only flow through a path provided external to the capacitor (e.g. when you place a resistor across it's terminals).
Or simply put - current charges the capacitor so if voltage increases the charge increases - and if the voltage decreases so does the charge(discharges the cap). So 2 equations come to mind. Q= I*t and Q=C*V Q= charge-coulombs I= current C= capacitance V=voltage and t=time
The capacitor's momentary current ic(t) is equal to the capacitance of the capacitor,
times the derivative of the momentary capacitor's voltage vc(t):
ic=C* dv/dt http://www.rapidtables.com/electric/capacitor.htm http://actpcb.com/capacitor-calculator Capacitor is an electronic component that stores electric charge. The capacitor is made of 2 close conductors (usually plates) that are separated by a dielectric material. The plates accumulate electric charge when connected to power source. One plate accumulates positive charge and the other plate accumulates negative charge.
The capacitance is the amount of electric charge that is stored in the capacitor at voltage of 1 Volt.
The capacitance is measured in units of Farad (F).
The capacitor disconnects current in direct current (DC) circuits and short circuit in alternating current (AC) circuits.
Having no conduction path (I.E. no conductor between the two terminals) a capacitor will not support _conduction charge flow_. But having capacitance between the two terminals it will support _displacement charge flow_.
It's funny but with "current" being "charge flow", when one says "current flow" they are saying "charge flow flow."
It's also the case that the plates [on a capacitor] can be both charged positive or both charged negative, but have merely a difference of charge. It's doesn't have to be the case where one has accumulated positive charge and the other negative charge.
A better way of describing the charge on a capacitor is to say that there is a difference of charge.
