# Potential difference between charged parallel plates

• Robin64
In summary, when calculating the potential difference between two parallel plates, it is typically done using the E-field and distance between the plates. However, if using the formula V=kq/r, which is for forces between two point particles, the issue of r=0 arises. This can be dealt with by focusing on a positively charged particle on the positive plate and the forces between that and the moving positive particle. Due to the conductive nature of the plate, the other positive particles will move away from the point on the plate that the particle is approaching, preventing r from ever being zero. Even if the particle is attached to the plate, a new equilibrium will be achieved. This consideration was overlooked in the conversation.

#### Robin64

So we know that the E-field between two parallel plates is constant and that the potential difference between the plates is just the E-field times the distance between the plates. Let's say we're moving a positive charge from a negatively charged plate to a positively charge plate ( or near), and instead of using the E-field and distance between the plates to calculate the potential difference, we instead just want to use the formula for electric potential, V=kq/r. How do we deal with the r=0 that inevitably crops up?

The V=kq/r formula is for forces between two point particles, not two plates. To use it you need to focus on a positively charged particle, call it p, on the positive plate, and the forces between that and the moving positive particle, call it q. But since the plate is conductive, as q nears the plate, p, as well as all other positive particles, will move away from the point on the plate that q is approaching, so we will never get to a situation where r is zero. Even if we could somehow attach q immovably to a point on the plate, a new equilibrium would be achieved in which all the other positive particles arrange themselves at a distance from p.

That makes sense. I completely forgot to consider that the charge redistribution that would occur with a charge near a plate with like charge.

Thanks.

## 1. What is the potential difference between charged parallel plates?

The potential difference between charged parallel plates is the difference in electric potential energy per unit charge between the two plates. It is measured in volts (V) and is a measure of the strength of the electric field between the plates.

## 2. How is the potential difference between charged parallel plates calculated?

The potential difference between charged parallel plates is calculated by dividing the difference in potential energy (measured in joules) by the magnitude of the charge (measured in coulombs) of the charged particles between the plates. This can be represented by the equation V = ΔU/q.

## 3. What factors affect the potential difference between charged parallel plates?

The potential difference between charged parallel plates is affected by the distance between the plates, the magnitude and distribution of the charges on the plates, and the dielectric material between the plates. It is also affected by any external influences such as other charges or electric fields.

## 4. How does the potential difference between charged parallel plates relate to electric potential energy?

The potential difference between charged parallel plates is directly proportional to the electric potential energy. This means that as the potential difference increases, so does the electric potential energy. This relationship is represented by the equation ΔU = qV.

## 5. What is the purpose of studying the potential difference between charged parallel plates?

Studying the potential difference between charged parallel plates allows scientists to understand and manipulate electric fields. It also has practical applications, such as in capacitors and other electrical devices. Additionally, this knowledge is important in the study of electromagnetism and the behavior of charged particles in electric fields.