Chapter 8: Electric Field

Field of force

A region of space where an object feels a force.

  • Electric Field: It is the objects with electric field
  • Magnetic Field: It is magnetic materials and moving charges.
  • Gravitational field: it is objects with mass.


Field Lines

The lines drawn to represent the strength and direction of field of force.


Field lines are drawn to represent an electric field.

Electric Field strength


Electric field strength (E) is defined as; at a point is the force per unit charge exerted on a stationary positive charge at that point. i.e. E=F/Q
It follows that the units of electric field strength are newtons per coulomb (NC^-1).
The strength of the electric field between two parallel plates depends on:
Voltage v between the plates
The separation d between the plate
The formula to calculate the force on charge Q in uniform field between two parallel plates is:
F=QE= -QV/d
F=eV/d (for an electron)

An electric charge moves in a parabolic path while moving at a right angle to a uniform electric field.