• An electric field is a region of space in which an electric charge “feels” a force
• The?electric field strength?at a point is defined as:

The electrostatic force per unit positive charge acting on the charge at that point

• The electric field strength can be calculated using the equation:

• Where:
  • E?= electric field strength (N C-1)
  • F?= electrostatic force on the charge (N)
  • Q?= charge (C)

   

• It is important to use a positive?test charge?in this definition, as this determines the direction of the electric field
• The electric field strength is a?vector?quantity, it is always directed:
  • Away?from a positive charge
  • Towards?a negative charge

   

• Recall that?opposite charges?(positive and negative) charges?attract?each other
• Conversely,?like charges?(positive and positive or negative and negative)?repel?each other