Question

The potential of the electric field produced by a point charge at any point $(x, y, z)$ is given by $V= 3x^{2} + 5$ , where $x, y, z$ are in metres and $V$ is in volts. The intensity of the electric field at $(-2,1,0)$ is

• A. $+17 \,V\,m^{-1}$
• B. $-17\,V\,m^{-1}$
• C. $+12\,v\,m^{-1}$
• D. $-12\,V\,m^{-1}$

Answer 1

Answer: (C)

$+12\,v\,m^{-1}$

Answer 2

Potential $( V )=3 x ^{2}+5$
Intensity of the electric field, $E=\frac{-d V}{d x}$
$\therefore E =-\frac{ d \left(3 x ^{2}+5\right)}{ dx }=-6 x$
$\left.\therefore E \right|_{ x =-2}=-6(-2)=12 V / m$