## 4 Charges at a Square

- Category: Shortcuts
- Written by fisikastudycenter

4 charges with the same in sign are located at a square as this below figure. You have to determine the coulomb force at one of the charges, the length of square side is **a** meter.

Here is an alternative solution for this case, you might have your own. Choose one charge, in this solution q_{3} is choosen. Sketch the all electrostatic forces that are acting on it cause of its interactions with the other charges. See the figure below

Find the magnitudes of each forces F_{32}, F_{34} and F_{31}

The next step, you have to sum F_{32} and F_{34}, of course in a vector operation, the angle is 90°. Keep in mind that kq^{2}/a^{2 }named F in here to simplify the calculations.

Finally insert the values of F and k to get the final result. The same method and the same results can be applied for the three other charges.