Superposition is the linear addition of the electric fields created by multiple charged particles. By Newton's second law, the net force on a charge q is given by the sum of forces due to other charges in the vicinity of q. The force on q can be represented in terms of the individual fields produced by the other charges as a sum of the fields.
For two like charges the electric field looks significantly different than for the dipole. The electric field for two positive charges.
Note that at the midpoint between the charges there is a hole in the field. The electric field goes to zero there. Elsewhere on the line perpendicular to the line joining the two charges, the field is not zero and becomes fairly strong.
Why is this variation in the field happening?
We are now going to explore this arrangement of charge using "Electric Field Hockey" in Exercise2.