Electrostatics

A charge Q is placed at each of the opposite corners of a square. A charge q is placed at each of the other two corners. If the net electrical force on Q is zero, then Q/q equals

  1. -1
  2. 1
  3. -2√2
  4. -1/√2

Answer

(KQ)/(2a2) = (√2)KQ/a2

|Q/q| = 2√2

So,

Q/q = -2√2

The correct option is C.