Answer:
[tex]Q = 21.09 \times 10^{-8} C[/tex]
Explanation:
We know from theory that the magnitude of the force between two charges is measured by the expression
[tex]F=\frac1{4\pi\epsilon} \frac{Qq}{r^2}[/tex]
We know that two spheres have the same charge, and let's assume they're in a vacuum, so [tex]\epsilon = \epsilon_0 =8.85\times10^{-12} C^2/Nm^2[/tex]
At this point we can solve for Q
[tex]Q^2 = 4\pi\epsilon F r^2 = 4\pi \times (8.85 \times 10^-12)\times (6\times 10^-3) \times (2 \times 10^-1)^2 = 444.624 \times 10^{-17} = 4446.24\times 10^-16 C^2 \rightarrow Q = 21.09 \times 10^{-8} C[/tex]
Double check calculations for safety, as usual