Energy density of charged capacitor via QFT

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Thread starter Spinnor
Start date Jul 4, 2016
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Capacitor Charged Density Energy Energy density Qft

In summary, energy density in the context of a charged capacitor refers to the amount of energy stored per unit volume between the plates. It can be calculated using Quantum Field Theory (QFT) and is affected by factors such as distance between plates, electric charge, and dielectric constant. As the charge on the plates increases, so does the energy density, but there is a limit before the capacitor breaks down. In practical applications, energy density plays a significant role in determining the storage and efficiency of electronic devices.

Jul 4, 2016

Spinnor

Gold Member

From the view point of quantum field theory how does one describe the electromagnetic energy density between the plates of a charged capacitor?

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Jul 5, 2016

Paul Colby

Insights Author

Gold Member

When using the coulomb gauge, a static electric field appears as a classical field component.

1. What is energy density in the context of a charged capacitor?

In the context of a charged capacitor, energy density refers to the amount of energy stored per unit volume between the plates of the capacitor. It is a measure of the electric field strength within the capacitor.

2. How is energy density calculated in a charged capacitor using QFT?

The energy density of a charged capacitor can be calculated using Quantum Field Theory (QFT) by taking the expectation value of the energy-momentum tensor. This involves summing over all possible quantum states of the electric field between the plates of the capacitor.

3. What factors affect the energy density of a charged capacitor?

The energy density of a charged capacitor is affected by the distance between the plates, the magnitude of the electric charge on the plates, and the dielectric constant of the material between the plates. It is also affected by the geometry of the capacitor, such as the shape and size of the plates.

4. How does the energy density of a charged capacitor change as the charge on the plates increases?

As the charge on the plates of a capacitor increases, the energy density also increases. This is because the electric field between the plates becomes stronger, leading to a higher energy density. However, there is a limit to how much charge can be stored on the plates before the capacitor breaks down.

5. What is the significance of the energy density of a charged capacitor in practical applications?

The energy density of a charged capacitor is an important factor in practical applications, such as in electronic devices. It determines the amount of energy that can be stored in the capacitor and how efficiently it can be used. A higher energy density allows for longer lasting and more powerful devices, while a lower energy density may result in shorter battery life and weaker performance.