Answer to Question #88166 in Electricity and Magnetism for Momoh walter

Question

Three point charges of 3µC, 8µC and 5µC are located at the corners of an equilateral triangle of side 0.4m, calculate the net force on the 8µC?

Answer 1

The components of a net force on a second charge

$$F=\sqrt{F_{12}^2+F_{32}^2-2F_{12}F_{32}\cos 120^{\circ}}$$

$$=\frac{k q_2}{a^2}\sqrt{q_1^2+q_3^2+q_1q_3}$$

$$=\frac{9\times 10^9\times 8\times 10^{-6}}{(0.4)^2}\sqrt{3^2+5^2+3\times 5}\times 10^{-6}$$

$$=3.15\:\rm{N}$$