Four point charges, each of magnitude 18.45 µc, are placed at the corners of a square 21.7 cm on a side. if three of the charges are positive and one is negative, find the magnitude of the force expe

Four point charges, each of magnitude 18.45 µc, are placed at the corners of a square 21.7 cm on a side. if three of the charges are positive and one is negative, find the magnitude of the force experienced by the negative charge. the value of coulomb's constant is 8.98755 × 109 n · m 2 /c 2 .