The magnitude of that other charge will be 9×10⁻⁵ C. The force on the charge is inverse of the distance.
The force of attraction between two charges, according to Coulomb's law, is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.
The magnitude of that other charge is found as;
[tex]\rm F = \frac{Kq_1q_2}{r^2} \\\\ \rm 9 = \frac{9 \times 10^9 \times 1\times 10^{-4}\times q_2}{(3)^2} \\\\ q_2=9\times 10^{-5} \ C[/tex]
Hence, the magnitude of that other charge will be 9×10⁻⁵ C.
To learn more about Columb's law, refer to the link;
brainly.com/question/1616890
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