Identical +3.92 ìC 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?

Answer 1

φ =k•q/r
φ1+ φ2 + φ3 =0
k•q1/a + k•q2/a√2 + k•q3/a =0
q3= q1 + q2/√2 =3.92(1+1/√2) =
= 6.69 μC