Question

A +100μC charged is place at the origin. A +200μC charge is place 2m above the origin and a -300μC charged is placed on 3m to the right of the origin. What is the magnitude and direction of the net force acting on the charge placed at the origin?

Answer 1

$F_1 = \frac{9 \times 10^9 \times 100 \times 300 \times 10^{-12}}{9} = 30 \;N \\ F_2 = \frac{9 \times 10^9 \times 100 \times 200 \times 10^{-12}}{4} = 45 \;N \\ F = \sqrt{F_1^2 +F^2_2} = 54.08 \;N$

$θ=180 +α \\ = 180 + tan^{-1}(\frac{45}{30}) \\ = 236.31$