two Identical point charges are fixed to diagonally oppositecorners of a square.

Question

two Identical point charges are fixed to diagonally oppositecorners of a square. where does a third point charge experience thegreater force? a)at one of the empty cornors b)at the center of the square c)it depends on the sign of the third charge d)the force in the center is equal to the force at one ofthe empty cornors
I think it is c because like charges repel each other. two Identical point charges are fixed to diagonally oppositecorners of a square. where does a third point charge experience thegreater force? a)at one of the empty cornors b)at the center of the square c)it depends on the sign of the third charge d)the force in the center is equal to the force at one ofthe empty cornors

Explanation / Answer

the answer is a. b) at the center of the square, the force on the 3rd charge iszero. this is true regardless of the sign of the third charge. (ifthe 3rd charge is the same as the other two charges, then the 3rdcharge will be equally attracted to both of the two charges, makingthe net force on the 3rd charge zero. similarly, if the 3rd chargeis opposite the other two charges, then the 3rd charge will beequally repelled from the two charges, making the net force on the3rd charge zero) c) with your choice of positions in this question, it doesn'tmatter what the charge of the 3rd is (according to what I said in band d) d) in the center, you only have components of force acting alongthe same axis. since the third charge is equidistant from the twocharges, AND the two point charges are identical (in magnitude andcharge), this means that at this point, your net force equalszero. however, if you consider ANY other point equidistant from the twopoints, you will no longer have their force components acting alongone axis. in this case, you will have a nonzero net force eitherpointing straight up (if your 3rd charge is the same as the firsttwo), or straight down (if your 3rd charge is opposite the firsttwo). at either of the two empty corners, you will be at one ofthese equidistant points.

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