question_answer

In fig., 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) 0.23 N in the +x-direction

B) 0.46 N in the +x-direction

C) 0.23 N in the +x-direction

D) 0.46 N in the +x-direction

Correct Answer: B

Solution :

[b] \[{{F}_{net}}=2|{{F}_{31}}|cos\alpha \] \[=2\times \frac{1}{4\pi {{\varepsilon }_{0}}}\times \frac{2\times 4\times {{10}^{-12}}}{{{\left( 0.5 \right)}^{2}}}\times \frac{4}{5}=0.46N\]