Electric Field Intensity

Description:

Intensity of Electric Field at a point is measured by the force being experienced by a unit charge  placed at that point. It is denoted by ‘E→’.

Force (F) on a charge q is directly proportional to the electric charge (q).

F ∝ q .........(1)

Force (F) on a charge is directly proportional to the intensity of electric field (E).

F ∝ E .........(2)

On combining (1) and (2) we get −

F ∝ qE .........(3)

On Introducing a proportionality constant in equation (3) we get −

F→ = kqE→

E→ = kF→/q .........(4)

Here we define the electric field. If a unit charge is taken at any location and Electric field is such that it experiences force F = 1N then, the intensity of electric field at this location is also 1unit.

Putting these values in eq (4) we get −

k = 1

when k=1,

E→ = F→/q

F→ = qE→

Or,

If q is a unit charge (i.e q=1), then electric field intensity (E) is equal to the force applied on electric charge.

OR

Force per unit charge gives electric field intensity at that point.