Question

the net force on unknown charge is zero. what os distance between Q1 and Q2.

Distance between Q and Q1 is 50 cm, Q1 = 30×10-6 C and Q2 = 60×10-6 C.

Answer 1

$F_1=F_2,$

$F_2=\frac{kQ_1Q}{d_1^2},$

$F_2=\frac{kQQ_2}{d_2^2},$

$\frac{Q_1}{d_1^2}=\frac{Q_2}{d_2^2},$

$d_2=d_1\sqrt{\frac{Q_2}{Q_1}},$

$d=d_1+d_2=d_1(1+\sqrt{\frac{Q_2}{Q_1}}),$

$d=0.5\cdot (1+\sqrt{2})=1.2~m.$