Electric field in capacitors

In summary, when a capacitor is connected to a battery, electrons will transfer between the negative terminal and the negative plate of the capacitor until the potential is equal. This causes the electric field inside the wire to become zero and the electrons to stop moving. The same process happens when the positive plate is connected to the positive terminal. After a short time, steady state is reached and the potential difference between the plates is solely determined by the battery. This potential difference can be measured with respect to any reference point with zero potential, such as the negative terminal of the battery.
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Homework Statement


In a capacitor, is the potential difference at the battery causing an electric field flow inside the wire connected to the two plates of the capacitor? But like at the negative terminal of the battery, the potential is zero, so does that mean that the negative plate of the capacitor is also zero and that means that the electrons will move so that the potential difference is zero between the two plates? But like apparently the electric field once equilibrium is reached becomes zero...why is that because I thought that there is still a potential difference in the battery? It says in my textbook that 'once this equilibrium is reached, a potential difference no longer exists between the terminal and the plate; as a result no electric field is present in the wire and the electrons stop moving.'


Homework Equations





The Attempt at a Solution

 
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  • #2
At the instant when you connect a plate of the capacitor to the negative terminal of a battery, electrons will be transferred to the plate till the potential on the plate is the same as that of the terminal. After this happens, there is no electric field inside the wire and the electrons stop moving. When you connect the other plate to the positive terminal, the same happens, but the electrons will flow away from the plate to the positive terminal of the battery and the plate takes the same potential as the positive terminal of the battery. This happens in a very short time, depending on the resistance of the connecting wires and the the value of the capacitance.
After this short time, steady state is reached and the potential of one plate is equal to the potential of the terminal it is connected with. Therefore the potential difference between the plates is the same as the potential difference between the terminals, and this potential difference is determined solely by the battery.

You can not measure potential itself, but potential difference only. With respect to infinity, with respect to the ground, or with respect to any point of an electric circuit. This reference point with zero potential can be the negative terminal of the battery.

ehild
 

1. What is an electric field in a capacitor?

The electric field in a capacitor is a region in which electrically charged particles experience a force due to the presence of an electric charge. It is created by the separation of positive and negative charges on the plates of the capacitor.

2. How is the electric field strength in a capacitor determined?

The electric field strength in a capacitor is determined by the voltage between the plates divided by the distance between the plates. It is represented in units of volts per meter (V/m).

3. How does the electric field change when the distance between the plates of a capacitor increases?

The electric field decreases as the distance between the plates of a capacitor increases. This is because the voltage remains constant, but the distance between the plates increases, resulting in a decrease in the electric field strength.

4. Does the electric field in a capacitor depend on the type of dielectric material used?

Yes, the electric field in a capacitor is affected by the type of dielectric material used between the plates. Different materials have different permittivity values, which determine the electric field strength in the capacitor.

5. Can the electric field in a capacitor be changed by changing the charge on the plates?

Yes, the electric field in a capacitor can be changed by changing the charge on the plates. The electric field strength is directly proportional to the charge on the plates, so increasing or decreasing the charge will result in a corresponding change in the electric field strength.

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