Target Exam

CUET

Subject

Physics

Chapter

Electrostatic Potential and Capacitance

Question:

Assume an electric field $E = 30 x \hat i$ exists in space. If $V_0$ is the potential at the origin and $V_A$ is the potential at $x = 2 m$, then the potential difference $V_A- V_0$ is

Options:

-40 V

-60 V

0 V

60 V

Correct Answer:

-60 V

Explanation:

The correct answer is Option (2) → -60 V

Given electric field: $\vec{E} = 30x\,\hat{i}$

Relation between electric field and potential:

$E_x = -\frac{dV}{dx}$

$\Rightarrow \frac{dV}{dx} = -30x$

Integrating from $x = 0$ to $x = 2$:

$V_A - V_0 = \int_{0}^{2} \frac{dV}{dx} \, dx = \int_{0}^{2} (-30x)\,dx$

$V_A - V_0 = -30 \left[\frac{x^2}{2}\right]_0^2 = -30 \left(\frac{4}{2}\right)$

$V_A - V_0 = -60\,V$

Potential difference $V_A - V_0 = -60\,V$