Two point charges of unknown magnitude and sign are a distance d apart.If the electric field strength is zero at a point between them on the line joining them,you can conclude that
A)the charges are equal in magnitude but opposite in sign.
B)the charges are equal in magnitude and have the same sign.
C)the charges are not necessarily equal in magnitude but have opposite signs.
D)the charges are not necessarily equal in magnitude but have the same sign.
E)there is not enough information to say anything specific about the charges.

Question

Quizplus · Accepted Answer

If the electric field strength is zero at a point between the two charges, it means the field due to one charge is equal and opposite to the field due to the other charge at that point. This can only happen if the charges are equal in magnitude but opposite in sign, as only then the fields due to the charges cancel each other.Here, there are no other possibilities for charges so the answer has to be A.

Two Point Charges of Unknown Magnitude and Sign Are a Distance