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Electric Charges And Fields

Question
CBSEENPH12037217

The electric field E due to a point charge at any point near it is defined as E = limq0Fq, where q is the test charge and F is the force acting on it. What is the physical significance of limq0 in this expression? Draw the electric field lines of a point charge Q when (i) Q > 0 and (ii) Q < 0

Solution
It is indicated by the limq0  that the test charge q is so small that its presence does not disturb the distribution of source charge and therefore, its electric field.
The electric fields of the point charge Q are shown below.