Answer to Question #96585 in Electricity and Magnetism for Chava

Question

Three point charges, q1=+5x10-6C, q2=-8x10-6C and q3=+2x10-6C, are placed on the corners of an equilateral triangle with sides of length 120 mm. Find the magnitude and direction of the net force over charge q1=+5x10-6C (use 2 decimal plates)

Answer 1

$q_2$ will attract $q_1$ and $q_3$ will repel $q_1$

Force on $q_1$ by $q_3=F_1=\frac{K\times q_1\times q_3}{r^2}=6.250N$

Force on $q_1$ by $q_2=F_2=\frac{K\times q_1\times q_2}{r^2}=25N$

Hence resultant force on $q_1=\sqrt{F_1^2+F_2^2+2F_1F_2cos\theta}=507.81N$