Parallel plates are a simple way of creating a uniform electric field. The field is created by applying a voltage difference between the plates.

Example of the electric field lines between two parallel plates

Calculating the Electric Field

The electric field between two parallel plates is constant so it can be calculated as follows:

• Definitions
  • is the electric field vector at that point (it will point from the positive plate to the negative plate)
  • is the voltage difference between the two plates
  • is the distance between the two plates measured in meters (m)

Examples

Two Parallel Plates Are 12 Cm Apart, Each with a Voltage of 400 V

What is the Electric Field between the Plates?

Find the Work Required to Move a Proton from the Negative Plate to the Positive Plate

Find the Speed of an Electron at the Positive Plate if it is Released from Rest at the Negative Plate