What happens when direct current is passed through capacitor?
Answers
Answer:
A capacitor is a passive device that stores energy in its electric field and returns energy to the circuit whenever required. a capacitor consists of two conducting plates separated by an insulating material or dielectric. the figure below is the basic structure of the capacitor.
When a capacitor is connected to a circuit with direct current(DC) source there are two processes to happen in specific conditions
1)Charging
2)Discharging
when the capacitor is connected to a DC power supply and the current flows through the circuit. Both plates get equal and opposite charges and an increasing potential difference, Vc is created while the capacitor is charging. once the voltage at the terminals of the capacitor,Vc is equal to the power supply voltage, i.e., Vc = V, the capacitor is fully charged and the current stops flowing through the circuit, the charging phase is over. in the figure below the capacitor is charging.
A capacitor is equivalent to an open-circuit to direct current R = ∞, because once the charging phase has completed, no more current flows through it. the voltage Vc on a capacitor cannot charge continuously. when the capacitor is disconnected from the power-supply the capacitor is discharging through the resistor Rd and the voltage between plated drops down to 0, Vc=0. below figure illustrates the discharging phase.
The product of Resistance and capacitance is called the Time constant T of the capacitor , what characterizes the rate of charging and discharging of a capacitor . you can see how time-constant affects the charging and discharging of the capacitor in the below figure.
The smaller the resistance or capacitance the smaller the charging and discharging rate of the capacitor, and vice versa.
Capacitors are found in almost all electronic circuits. they can be used as a fast battery, for example a capacitor is a storehouse of energy in photo-flash unit that releases energy quickly during short period of time.