A point charge is used to determine the electric field around a charged particle. Why is it necessary that the point charge does not affect the position of the charge being tested?

A test charge should be small enough not to move the charge creating the field. If it did move, the distance between the charges would change, and the electric field strength depends on the inverse square of that distance: E = kQ/r². Thus even a change in position would alter the field being measured. The correct choice is “Electric fields are inversely proportional to the square of the distance.”

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