What happen when a plate of charged capacitor is earthed?

In summary, a capacitor is charged with a potential difference. When the capacitor is disconnected from battery and ground, the potential on one of the plates will become zero.
  • #1
vkash
318
1

Homework Statement



A capacitor is charged with some potential difference. A charge will developed on both of it's plates. Now remove this capacitor from battery and ground/earth one of the plate through a wire. What will happen??

Homework Equations



gauss law

The Attempt at a Solution



Potential of the surface that is earthed should became zero but in this case how to manage other things like charge on the other plate so the electric field inside metal plates of the capacitor remain zero.

[highlight] NOTE: all the things are talked about parallel plate capacitor[/highlight]
 
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  • #2
friends please reply.
 
  • #3
Not much happens. Before making contact the capacitor is a net neutral object (even if the charges inside are separated to some degree). After making contact, the plate in contact with the Earth then has the same potential as the Earth. But no charges flow because there's not a complete circuit, and because the charges on either plate are attracting each other and holding them to the inside plate surfaces. The capacitor is still a net neutral object (as it the Earth).
 
  • #4
gneill said:
Not much happens. Before making contact the capacitor is a net neutral object (even if the charges inside are separated to some degree). After making contact, the plate in contact with the Earth then has the same potential as the Earth. But no charges flow because there's not a complete circuit, and because the charges on either plate are attracting each other and holding them to the inside plate surfaces. The capacitor is still a net neutral object (as it the Earth).

Yeah that is what i think.
But let us think in this way. what the potential of the plate that is connected to earth. let me say that is negative plate then potential at this plate is not zero But the potential of the Earth is zero. So here two objects are connected through conducing wire one with higher potential and other with lower potential so there must something that make this potential difference zero,
 
  • #5
Potential is a relative thing. The negative plate has a potential WITH RESPECT TO the positive plate, but the capacitor as a whole is neutral. It would take no work to move that capacitor anywhere you wish in an electric field. Connecting either plate to the Earth would only serve to establish its potential as being the same as that of the Earth.
 
  • #6
I used to service, repair and restore tube-driven guitar amplifiers. The method I used was to connect the caps feeding the B+ rail with ground, using jumpers and a bleed resistor to prevent sudden discharge. Keep the caps connected to ground all the time you've got your fingers in the chassis because those big caps have some "memory" and can re-develop a charge.

Use brightly-colored (fluorescent) jumpers so that you remember to remove them before buttoning up the amp and powering up.
 
  • #7
gneill said:
Potential is a relative thing. The negative plate has a potential WITH RESPECT TO the positive plate, but the capacitor as a whole is neutral. It would take no work to move that capacitor anywhere you wish in an electric field. Connecting either plate to the Earth would only serve to establish its potential as being the same as that of the Earth.
I like your answer but it is still doubt, I will discuss with my physics teacher.
thanks both the persons.
 

1. What is a charged capacitor?

A capacitor is a passive electronic component that is used to store electrical energy in the form of an electric field. It is made up of two conductive plates that are separated by an insulating material called a dielectric.

2. What happens when a plate of a charged capacitor is earthed?

When a plate of a charged capacitor is connected to the ground or earth, it allows the flow of excess charge from the capacitor to the ground. This process is called discharging and it results in the capacitor losing its stored energy.

3. Why is it important to earth a charged capacitor?

If a capacitor is not earthed, it can hold a high amount of electric charge which can be dangerous if touched. By earthing a charged capacitor, the excess charge is safely discharged and the risk of electrical shock is minimized.

4. How does earthing affect the capacitance of a charged capacitor?

Earthing a charged capacitor does not affect its capacitance. The capacitance of a capacitor is determined by its physical properties such as the distance between the plates and the type of dielectric used, and not by the presence or absence of an earth connection.

5. Can a charged capacitor be recharged after being earthed?

Yes, a capacitor can be recharged after being earthed. Once the excess charge has been discharged, the capacitor can be safely recharged and used again. However, it is important to handle capacitors with caution and to follow proper safety measures when working with charged capacitors.

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