The strength of electric field at a particular point is called as Electric Field intensity. In other words, the force felt by a unit positive charge situated at a point is called Electric field intensity. If 
is the force working on a test charge q0 at any point r, then the electric field intensity due to this will be:
Electric field intensity is a vector quantity means it has magnitude as well as direction. The direction of 
is similar to that of means is in the similar direction in which the test charge q 0 tends to go.
Newton per coulomb is the S.I. unit of Electric field intensity. Electric field is generated by a source charge placed anywhere. The charge present at source can be a combination of a no. of different charges or it may be a single charge or any continuous distribution of charge. The test charge +q 0 can have its self electric field, which have the ability to modify the electric field of the charge present at source. So, to reduce or remove its effect, we will write the equation of electric field intensity in some different way.
————-2.1
As we know that the charge 
is inversely proportional to the electric field intensity 
So as we increase the charge electric field intensity decreases. Due to the charges having individual nature the minimum value of charge is 1.6 X 10 -19 coulomb. The value of charge can never be zero.
The major importance and use of electric field is that, it can be used to calculate the direction and magnitude of the force felt by a charge present at a particular point affected by electric field. The equation showing the above result is given below:
———- 2.2
Note: The direction of electric field intensity is same as that of direction of force applied on a positive charge.
| No. | Field Location | Value of E N/C or V/m |
| 1. | In a molecule of Hydrogen | 5 X 1011 |
| 2. | Near to a charged comb | 103 |
| 3. | Present in the copper wiring of houses | 10-2 |
| 4. | On outermost layer of uranium nucleus | 3 X 1021 |
