Electric field intensity at a point can be defined as the force exerted per unit charge at that point.

The electric field intensity at a point is the force experienced by a unit of positive charge placed at that point.
Electric field intensity is a vector quantity.
It is denoted by ‘E’.
The formula is given by:
Electric field = F
q
or

E = KQ/r² = V/r

Unit of E is NC^-1 or Vm^-1.
The electric field intensity due to a positive charge is always directed away from the charge, and the intensity due to a negative charge is always directed towards the charge.

• Example 1: A student is at a height of 4m above the ground during a thunderstorm. Given that the potential difference between the thunder cloud and the cloud is 10⁷V. calculate the electric field created by the storm
solution
E = v/r
where V = potential difference
r = distance
E = 10⁷ = 2.5 x10⁶ Vm^-1
4
• Example 2: In a uniform electric field, the magnitude of the force on a charge of 0.2C is 4x10³N. Calculate the electric field intensity
solution
E = F/q
where F = force
q = charge
E = 4x10³ = 2 x 10⁴NC^-1
0.2