Three point charges
Q₁, Q₂ and Q₃ in that order are placed equally spaced along a straight line. Q₂
and Q₃ are equal in magnitude but opposite in sign. If the net force on Q₃ is zero, the value of Q₁ is :
a Q₁=√2Q₃
b Q₁=Q₃
c Q₁=2Q₃
d Q₁=4Q₃