Four point charges of magnitude 3.6 mu or micro cc are at the corners of a square of side 4 m. (a) find the electrostatic potential energy if all of the charges are negative.

- 4.4 x 10⁴ J

Explanation:

q = charge on each point charge = - 3.6 x 10⁻⁶ C

a = length of side of square = 4 m

L = length of diagonal of the square

Length of the diagonal of the square is given as

L = a √2

L = 4 √2

L = 5.66 m

Electrostatic potential energy is given as

inserting the values

U = (4 (9 x 10⁹) (- 3.6 x 10⁻⁶)/4) + (2 (9 x 10⁹) (- 3.6 x 10⁻⁶)/5.66)

U = - 4.4 x 10⁴ J