An electric field is a field of force where a charged object experiences the force.
A field of force is represented by field lines. The separation between the field lines also shows the strength of the field.
The electric field strength at a point is the force exerted on a stationary positive charge at that point, per unit charge. If the field is formed between two parallel plates, then the electric field strength is the ratio of voltage to separation between the plate.
F/q is measured in Newton per Coulomb = NC¯¹
V/d is measured in Volt per Metre = Vm¯¹
- Sometimes you might be asked how does the force vary with the position in the electric field. It doesn’t. The force due to an electric field/or gravitational field is constant.
- Say we have two horizontal plates in a vacuum. The one above is Negative (-). An electron is shot from one side. It will travel horizontally at a constant velocity, but vertically it will accelerate downwards due to force F exerted by the electric field.