Solution:
Force on any corner charge
F1=kQa2, F2=kQ2a2, F3=kQ2(√2a)2
→F1+→F2+→F3=→F at equilibrium
Q22a2+√2Q2a2=Qq(a/√2)2
q=Q4(1+2√2)
Four charges equal to – Q are placed at the four corners of a square and a charge q is at its centre. If the system is in equilibrium, the value of q is
Force on any corner charge
F1=kQa2, F2=kQ2a2, F3=kQ2(√2a)2
→F1+→F2+→F3=→F at equilibrium
Q22a2+√2Q2a2=Qq(a/√2)2
q=Q4(1+2√2)