# Two balls, located at a distance of 10 cm from each other, have the same negative charges and interact with

**Two balls, located at a distance of 10 cm from each other, have the same negative charges and interact with a force of 0.23 mN. Find the charge of each ball.**

To find out the charge of each of the two balls, we use the formula (Coulomb’s law, we assume that these balls are located in vacuum or air): F = | q1 | * | q2 | * k / r ^ 2 = q2 * k / r ^ 2, whence we express: q2 = r ^ 2 * F / k and q = √ (r ^ 2 * F / k) = r * √ (F / k).

Const: k – coefficient of proportionality (k = 9 * 10 ^ 9 N * m2 / Kl)

Data: r – distance (r = 10 cm = 0.1 m); F is the force of interaction (F = 0.23 mN = 0.23 * 10 ^ -3 N).

Calculation: q = r * √ (F / k) = 0.1 * √ (0.23 * 10 ^ -3 / (9 * 10 ^ 9)) ≈ 1.6 * 10 ^ -8 C = 160 μC.

Answer: Each of the two balls must have a charge of 160 μC.