[tex]Dane:\\Q_1 = 0,04 \ C\\Q_2 = 0,05 \ C\\r = 50 \ cm = 0,5 \ m\\k = 9\cdot10^{9}\frac{Nm^{2}}{C^{2}}}\\Szukane:\\F = ?\\\\F = k\cdot\frac{Q_1\cdot Q_2}{r^{2}}\\\\F = 9\cdot10^{9}\frac{Nm^{2}}{C^{2}}\cdot\frac{0,04 \ C \cdot 0,05 \ C}{(0,5 \ m)^{2}}=9\cdot10^{9}\cdot\frac{0,002}{0,25} \ N=0,072\cdot10^{9} \ N\\\\\boxed{F = 7,2\cdot10^{11} \ N}[/tex]
