question_answer

A oil drop having a mass \[4.8\times {{10}^{-10}}\]and charge \[24\times {{10}^{-18}}C\] stands still between two charged horizontal plates separated by a distance of 1 cm. If now the polarity of the plates is changed, instantaneous acceleration of the drop is ( \[g=10\,m{{s}^{-2}}\])

A)  \[5m{{s}^{-2}}\]

B)  \[10\,m{{s}^{-2}}\]

C)  \[15\,m{{s}^{-2}}\]

D)  \[20\,m{{s}^{-2}}\]

Correct Answer: B

Solution :

  \[a=\frac{F}{m}\] \[=\frac{qE}{m}\] \[=\frac{mg}{m}\] \[g=10\,m/{{s}^{2}}\]