Iremos usar a simples fórmula:
F=k*q1*q2/d²
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temos que:
F=100N
q1=0,0025C
q2=0,004C
k=9*10^9Nm²/C²
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100=0,0025*0,004*9*10^9/d²
100=90000/d²
d²=90000/100
d²=900
d=30m
