Edexcel A Level (IAL) Physics-4.17 Electric Field between Parallel Plates- Study Notes- New Syllabus

Electric Field Between Parallel Plates \( E = \dfrac{V}{d} \)

When two large, flat, parallel conducting plates are connected to a potential difference, a uniform electric field is produced between them (ignoring edge effects).

Equation for Electric Field Between Parallel Plates

The magnitude of the electric field between the plates is given by:

\( E = \dfrac{V}{d} \)

• \( E \) = electric field strength (V m⁻¹ or N C⁻¹)
• \( V \) = potential difference between the plates (V)
• \( d \) = separation between the plates (m)

Conditions for Using This Equation

• The plates are large compared to their separation.
• The plates are parallel.
• The electric field between the plates is uniform.
• Edge effects are neglected.

Direction of the Electric Field

• The electric field points from the positive plate to the negative plate.
• The field direction is the direction of force on a positive test charge.

Link with Potential Gradient

Electric field strength is the potential gradient:

\( E = -\dfrac{\Delta V}{\Delta x} \)

For a uniform field, the potential changes linearly with distance, giving:

\( E = \dfrac{V}{d} \)

Relationship with Force on a Charge

A charge \( Q \) placed between the plates experiences a force:

\( F = EQ \)

This force is constant anywhere between the plates because the field is uniform.

 Applications

• Motion of charged particles between plates
• Electron deflection in cathode-ray tubes
• Capacitors
• Particle accelerators