Two point charges totalling 900 muc exeat a repulsive force

Two point charges totalling 9.00 muc exeat a repulsive force of 0.100 N on one another when by 0.849 m What is the charge on each? smallest charge What is the charge on each if the force is attractive?

Solution

q + Q = 9,00 muC

Q = 9.00 muC - q

F = k Q q / d²

0.100 N = 9 * 10⁹ * (9.00 muC - q ) * q / (0.849 m)²

0.100 N = (9 * 10⁹ * 9.00 * 10^-6 * q ) - (9 * 10⁹ * q² ) / (0.849 m)²

(9 * 10⁹ * q²) - 81000 q + 0.072 = 0

q = 8 muC

q = 1.00 muC

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If the force is attractive, then the force is negative

-0.100 N = (9 * 10⁹ * 9.00 * 10^-6 * q ) - (9 * 10⁹ * q² ) / (0.849 m)²

q = -0.815 muC

q = 9.8 muC