1) Assume that an electric field $E=30x^{2}\hat{i}$ exists in space . Then, the potential difference VA-VO, where V0 is the potential at the origin and VA the potential at x=2 m is A) 120 J B) -120 J C) -80 J D) 80 J Answer: Option CExplanation: As we know, potential difference VA-V0 is dV=-Edx $\int_{V_{0}}^{V_{A}} dV=-\int_{0}^{2} 30x^{2}dx$ $V_{A}-V_{0}=-30\times\left[\frac{x^{3}}{3}\right]_0^2$ = $-10\times[2^{3}-(0)^{3}]$ = $-10\times 8=-80J$
