question_answer

Three charges are placed at the vertices of an equilateral triangle of side ?a? as shown in the following figure. The force experienced by the charge placed at the vertex A in a direction normal to BC is                                  [AIIMS 2003]

A)            \[{{Q}^{2}}/(4\pi {{\varepsilon }_{0}}{{a}^{2}})\]

B)            \[-{{Q}^{2}}/(4\pi {{\varepsilon }_{0}}{{a}^{2}})\]

C)            Zero

D)            \[{{Q}^{2}}/(2\pi {{\varepsilon }_{0}}{{a}^{2}})\]

Correct Answer: C

Solution :

                     \[|\overrightarrow{{{F}_{B}}}|\,=\,\,|\overrightarrow{{{F}_{C}}}|=k.\frac{{{Q}^{2}}}{{{a}^{2}}}\] Hence force experienced by the charge at A in the direction normal to BC is zero.