question_answer

Three charges 1 \[\mu \]C, 1 \[\mu \]C and 2 \[\mu \]C sire kept at the vertices A, B and C of an equilateral triangle ABC of 10 cm side, respectively. The resultant force on the charge at C is

A)  0.9 N                                    

B)  1.8 N

C)  2.72 N                                 

D)  3.6 N

Correct Answer: D

Solution :

                 The situation is shown in figure. Force on C due to A \[{{F}_{AC}}=\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{{{q}_{A}}{{q}_{C}}}{r_{AC}^{2}}\] \[=\frac{9\times {{10}^{9}}\times 1\times 2\times {{10}^{-12}}}{{{(0.1)}^{2}}}=1.8N\] Similarly,     \[{{F}_{BC}}=1.8\,N\] Hence, net force on \[C={{F}_{AC}}+{{F}_{BC}}=3.6\,N\]