#### 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  Option 1) Option 2) Option 3) Option 4)

As we learnt in

Superposition of Electric field -

The resultant electric field at any point is equal to the vector sum of all the electric fields.

- wherein

Consider the four forces F1, F2, F3 and F4  acting on charge (-Q)   placed at A

For equilibrium, consider forces along DA and  equate the resultant to zero

Option 1)

Incorrect

Option 2)

Correct

Option 3)

Incorrect

Option 4)

Incorrect