physics charges

Test charge: a test charge is an object (usually a point particle) that has negligible charge, such that the electric field generated by the object itself can be ignored. The concept of test charge is useful when investigating the property of a given electric field, which would not be disturbed by the presence of the test charge.

Electric charge: it is a basic property of matter carried by some elementary particles. It can be either +ve or -ve.

Static charge: electic charge that accumulated on an object and is immobile.

Point charge: it is a hypothetical charge located at a single point in space. In other words, a point chagre possesses no physical dimension.