An oil drop having a mass \[4.8\times {{10}^{-10}}g\] 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\[(g=10\,\,m{{s}^{-2}})\]