Question

Two charged objects in a laboratory are brought to 0.22 meters away from each other. If the force between the spheres is 4,550 N and the charge on one object is 9.9 × 10-5 C, what is the charge on the other object?

Answer 1

The force acting between two charged objects (Coulomb force) is

$\displaystyle F = \frac{k q_1 q_2}{r^2}$

$\displaystyle q_2 = \frac{F r^2}{kq_1} = \frac{4550 \cdot0.22^2}{9 \cdot 10^9 \cdot 9.9 \cdot 10^{-5}} = 2.47 \cdot 10^{-4} \; C$

Answer: $2.47 \cdot 10^{-4} \; C$