Question

In figure, two equal positive point charges $q_1=q_2=2.0$ $\mu C$ interact with a third point charge $Q=4.0\mu C$. The magnitude, as well as direction, of the net force on $Q$ is

• A. $0.23N$ in the $+x$-direction
• B. $0.46N$ in the $+x$-direction
• C. $0.23N$ in the $-x$-direction
• D. $0.46N$ in the $-x$-direction

Answer 1

Answer: (B)

$F_{\text{net }}=2\left|F_{31}\right|\cos \alpha$
$=2\times \frac{1}{4\pi {\epsilon }_0}\times \frac{2\times 4\times 10^{-12}}{(0.5{)}^2}\times \frac{4}{5}=0.46N$