Posted by sara on .
Identical +7.74 ƒÊC charges are fixed to adjacent corners of a square. What charge (magnitude and algebraic sign) should be fixed to one of the empty corners, so that the total potential at the remaining empty corner is 0 V?
I thought that this is what i should do. But I cant get the correct answer...
the total potential is
V = k[7.74ƒÊC/r + 7.74ƒÊC/ã2 *r + q/r]
0 = k/a[(7.74ƒÊC+q)ã2 + 7.74ƒÊC]
or (7.74ƒÊC+q)ã2 =  7.74ƒÊC
q = 7.74ƒÊC[1+1/ã2]
So that gives me q=13.23. I am told that that is the wrong answer. Please help!

physics 
drwls,
This looks like a question posted earlier, but in less legible form. I believe BobPursley agreed with your answer. I also got the same answer.