Two unequal point charges q1 and q2 are held in place separated from each other.A point charge Q is placed somewhere between them at a point where it remains stationary when released.From this observation,we can conclude that q1 and q2 must either both be positive or both be negative.

Question

Quizplus · Accepted Answer

If the point charge Q remains stationary when released, it means that the net electrostatic force on Q is zero. This can only happen if the direction of the electric field due to q1 and q2 is opposite to the direction of the electric field due to Q at the point where it is placed. If q1 and q2 have opposite signs, their electric fields will also have opposite signs and cancel each other out at some point between them. But if q1 and q2 have the same sign, their electric fields will add up and there will be no point between them where the electric field due to Q is opposite to the net electric field due to q1 and q2. Therefore, q1 and q2 must either both be positive or both be negative.

Two Unequal Point Charges Q1 and Q2 Are Held in Place