Electric Field Formula

The electric field is a physical quantity that describes the force per unit charge experienced by a charged particle at a given point in space. It is represented by the symbol “E” and its unit is Newtons per Coulomb (N/C).

The electric field at a given point in space can be calculated using the following formula:

E = F / q

where E is the electric field, F is the force exerted on a charged particle at that point, and q is the charge of the particle.

Alternatively, for a point charge q at a distance r from the charge, the electric field is given by:

E = kq / r^2

where k is the Coulomb’s constant (k = 8.99 × 10^9 N·m^2/C^2).

This formula states that the electric field at a point in space due to a point charge is proportional to the magnitude of the charge and inversely proportional to the square of the distance between the point charge and the point where the electric field is being measured.

Example

Here’s an example of how to use the electric field formula:

Let’s say we have a point charge of +4 µC (microCoulombs) located at a distance of 2 meters from a point in space. What is the electric field at that point?

Using the formula E = kq / r^2, where k = 8.99 × 10^9 N·m^2/C^2, q = +4 µC (4 × 10^-6 C), and r = 2 m, we can calculate the electric field:

E = (8.99 × 10^9 N·m^2/C^2) × (+4 × 10^-6 C) / (2 m)^2 E = 4.49 N/C

So the electric field at that point is 4.49 N/C, which means that a charged particle with a charge of 1 Coulomb would experience a force of 4.49 N if placed at that point.