Electric Field between Parallel Plates (Edexcel International A Level Physics)

Electric Field between Parallel Plates

• The magnitude of the electric field strength in a uniform field between two charged parallel plates is defined as:

• Where:

  • E = electric field strength (V m^-1)

  • V = potential difference between the plates (V)

  • d = separation between the plates (m)

• The electric field strength is now defined by the units V m^–1 

  • Therefore, the units V m^–1 are equivalent to the units N C^–1

• The equation shows:

  • The greater the voltage (potential difference) between the plates, the stronger the field

  • The greater the separation between the plates, the weaker the field

• Remember this equation cannot be used to find the electric field strength around a point charge (since this would be a radial field)

• The direction of the electric field is from the plate connected to the positive terminal of the cell to the plate connected to the negative terminal

The E field strength between two charged parallel plates is the ratio of the potential difference and separation of the plates

• Note: if one of the parallel plates is earthed, it has a voltage of 0 V