question_answer

A charged particle of mass 0.003 gm is held stationary in space by placing it in a downward direction of electric field of \[6\times {{10}^{4}}N/C\]. Then the magnitude of the charge is [Orissa JEE 2002]

A)            \[5\times {{10}^{-4}}C\]

B)                                      \[5\times {{10}^{-10}}C\]

C)            \[-18\times {{10}^{-6}}C\]

D)                                      \[-5\times {{10}^{-9}}C\]

Correct Answer: B

Solution :

                     By using   Þ \[Q=\frac{mg}{E}=\frac{0.003\times {{10}^{-3}}\times 10}{6\times {{10}^{4}}}\]= \[5\times {{10}^{10}}C\]