Electric potential at any point is $V = -5x + 3y + \sqrt{15} z$,then the magnitude of the electric field is

The electric potential inside a charged sphere is given by $\phi = ar^2 + b$,where $r$ is the distance from the center,and $a$ and $b$ are constants. The charge density inside the sphere is .......

The electric potential $V$ is given as a function of distance $x$ $(m)$ by $V = (2x^2 + 10x - 9) \text{ V}$. The value of the electric field at $x = 1 \text{ m}$ is: (in $\text{ V/m}$)

The electric potential $V$ is given as a function of distance $x$ (metre) by $V = (4x^2 + 8x - 3) \ V$. The value of the electric field at $x = 0.5 \ m$,in $V/m$,is:

What is the angle between the maximum value of the potential gradient and the equipotential surface?

The figure shows the electric potential $V$ as a function of distance through five regions on the $x$-axis. Which of the following is true for the electric field $E$ in these regions?