Question

what is test charge define in minimum and best way

Answer 1

It is a charge with very little magnitude and has a minor effect when kept in a place.
Hope it helps and pls mark as the best asnwer . :-)

Answer 2

                        A test charge is a charge that is small enough so that the charge configuration you are looking at is not disturbed. If you were to bring a 1μC charge up against some giant 1C charge, the smaller "test" charge would not really affect the position of the charge configuration you're studying. This leaves the equations dipole mentioned fairly easy to deal with.

Hope it'd be useful pls choose it the brainliest answer.
CHEERS!!!
MASelvam IITian
Booksworm.