# Assume that an electric field $\;\overline{E} =30x^{2} \hat{i}\;$ exists in space .Then the potential difference $\;V_{A}-V_{O}\;$ , where $\;V_{O}\;$ is the potential at the origin and $\;V_{A}\;$ the potential at x=2 m is :
$(a)\;120\;J \qquad(b)\;-120\;J\qquad(c)\;-80\;J\qquad(d)\;80\;J$