What is the null point ?

Hint: There are electric charges which produce electric fields. Electric field is force per unit charge exerted on a very small positive charge when it is at rest. When there are 2 or more such charges there is a point where the effect of the field is zero.

Complete answer:
Consider there are 2 point charges, one positive(+q) and another also positive(+q). Let us imagine the electric fields produced by these 2 charges when placed a distance apart. In between these 2 charges there will be a point where the effect of electric field will be zero as the 2 fields cancel each other.

Null point: in physics null point in a field is the point where the field quantity is zero as the result of 2 or more opposing quantities completely cancelling each other.Let us look at few situations where null point arises: null point can arise in patterns of microphones, antennas and wheatstone bridges like(meter -bridge) and potentiometer. Null points are found in electric fields, gravitational fields and also magnetic fields. It signifies that the effects of these fields at that particular point is zero or null.

Note: The null point of the fields can be scalar, vector or even tensor. Like electric and magnetic fields are vector quantities and they have a null point , whereas relativity gravitation has a tensor field called Einstein tensor it also has a null point, and the electrostatic potentials and gravitational potentials are scalar quantities and they too have a null point.