Assume that an electric field $\mathrm{E}=30 \mathrm{x}^2 \mathrm{i}$ exists in space. If ' $\mathrm{V}_0$ '…
Assume that an electric field $\mathrm{E}=30 \mathrm{x}^2 \mathrm{i}$ exists in space. If ' $\mathrm{V}_0$ ' is the potential at the origin and ' $\mathrm{V}_{\mathrm{A}}$ is the potential at $\mathrm{x}=2 \mathrm{~m}$, then the potential difference $\left(\mathrm{V}_{\mathrm{A}}-\mathrm{V}_0\right)$ is
$-80 \mathrm{~J}$
$-120 \mathrm{~J}$
$80 \mathrm{~J}$
$120 \mathrm{~J}$
Solution
$\begin{aligned} & d V=\vec{E} \cdot d x \\ & \int_{V_0}^{V_A} d V=-\int_0^2 30 x^2 d x \\ & V_A-V_0=-\left[10 x^3\right]_0^2=-80 J\end{aligned}$