A charged capacitor will start to discharge immediately after the switch is thrown. The discharge rate is only limited by the resistor connected in series with the circuit. When the capacitor’s charge is completely depleted there is no current flow in the circuit.
A capacitor can be discharged by simply shorting its terminals. When the terminals are shorted electrons from its negative plate will travel to the positive plate and we will see a sudden flow of current in the circuit.
The Impact of Throwing the Switch on the Charge of the Capacitor
A capacitor is an electrical device that can store charge. To understand what happens to the charge on the capacitor immediately after the switch is thrown, first, we should understand how does a capacitor function.
How Does A Capacitor Store Charge
A simple capacitor has two parallel plates in it. There is usually a dielectric material in between the two terminals. When a potential difference is applied to the plates, one plate gets positively charged and the other negatively. The charge stored in the capacitor is proportional to the potential difference between the plates.
A Simple Rc Circuit For Discharging A Capacitor
A charged capacitor is connected in series with a resistor through a switch. When the switch is thrown the electrons from the negative plate of the capacitor travel to the positive plate. Thus, a flow of current is obtained in the circuit, the current is limited by the resistor connected in series with the capacitor.
Discharging Curve of a Capacitor
From the discharging curve of the capacitor, we see that the voltage level of the capacitor drops with time during discharging. The voltage level gradually decreases from 100% to 0% when the switch is closed.
What Is The Charge On The Capacitor After The Switch Has Been Closed For A Long Time?
The charge on the capacitor is 0 coulombs after the switch has been closed for a long time, i.e., the capacitor is completely discharged. All the electrons from the negative plate will be moved to the positive plate through the circuit, so the net charge stored in the capacitor will be zero.
What Will Be The Charge On The Capacitor A Long Time After The Switch Is Moved To Position 2?
Position 2 refers to the closed position of the switch. After a long time of closing the switch, the charge on the capacitor will be zero. As all the electrons from the negative plate of the capacitor will surely travel to the positive plate after a long time i.e., the capacitor will be completely discharged.
What Is The Charge On The Capacitor After A Long Time?
When a charged capacitor is kept for a long time, the capacitor automatically discharges. Because the dielectric material of the capacitor is not completely an insulator, it acts as a high-value resistor. It discharges the capacitor slowly over time.
Conclusion
When the switch is closed the capacitor will discharge rapidly if a resistor is not used in series to limit the current. After some time, the capacitor will be completely discharged, i.e., the charge in the capacitor will be zero coulombs.
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