Square and Potential

[Soaring Crane]

The absolute potential at the exact center of a square is 3 V when a charge of +Q is located at one of the square's corners. What is the absolutue potential at the square's center when each of the other corners is also filled with a charge of +Q?

I suppose you can't just multiply 3V*4 = 12 V? What's the correct of doing this problem?

Thanks.

[Curious3141]

Actually, you can just multiply by 4. Potentials are scalar and additive.

If you want to "prove" it from first principles, you have to integrate the electric field vector along a line normal to the square and passing thru' the square's center with respect to displacement from infinity to zero. But you would end up with the same expression.