A charge Q is placed at each of the two opposite corners of a square. A charge q is placed at each of the other two corners. If the resultant force on each charge q is zero, then which of the following statements are true?

q = \(\sqrt {2}\)Q q = -\(\sqrt {2}\)Q q = 2\(\sqrt {2}\)Q q = -2\(\sqrt {2}\)Q

q = -2\(\sqrt {2}\)Q

F =- 2kQq Sin 45/r2 + kq2/\(\sqrt {2 }\)r2 = 0  q = -2\(\sqrt {2}\)Q