Question

Two charges q1 = –6 μC and q2 = +10 μC are placed 12 cm apart. Another charge, q3 = −2 μC is placed in the middle as shown in Figure 6. Determine the magnitude and direction of the force acting on q3 by the charge q1 and q2

Answer 1

$F=\frac{K_e(q_1q_2)}{r^2}$

With no figure 6

It is assumed that the three charges lies on a straight line and $q_3$ is equidistant from $q_1$ and $q_2$

$F_{q\>_3}$ $=K_eq_{3}\sum_{i=1}^{2}\>\>\frac{q_i}{r_i^2}$

Taking $K_e=8.99×10^9Nm^2C^{-2}$

$Fq_3=8.99×10^9×-2×10^{-6}(\frac{-6×10^{-6}}{(0.06)^2}+\frac{10×10^{-6}}{(0.06)^2})$

$=-19.98N$