Given:

Let the force due to charge at corner B, C and D be F_B, F_C, F_D.

Charge at each corner, .

The side of square is.

By Pythagoras theorem,

The length of diagonal .

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Formula used:

By Coulomb’s law, the electric force is given by:

Where ϵ₀ is the permittivity of free space

k is the electrostatic constant

q₁ and q₂ are the magnitude of charges

r is the distance of separation between the charges

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Resolving F_C , we get

The net force is:

We know that

Hence, the magnitude of net force is