Two parallel metal plates separated by a distance d have a potential difference V across them - AQA - A-Level Physics - Question 16 - 2021 - Paper 2

To find the electrostatic force acting on a charge in an electric field, we can use the formula:

$F = QE$

where:

• $F$ is the force,
• $Q$ is the charge,
• $E$ is the electric field strength.

1. Calculate the Electric Field Strength (E): For two parallel plates, the electric field is given by: $E = \frac{V}{d}$ where:

   • $V$ is the potential difference,
   • $d$ is the separation between the plates.

2. Substitute E in the Force Equation: Substituting for $E$: $F = Q \left(\frac{V}{d}\right)$ Thus, the expression for the force becomes: $F = \frac{QV}{d}$

This means the magnitude of the electrostatic force acting on the particle is: rac{QV}{d}.