The electrostatic potential inside a charged spherical ball is given by : $V = b -ar^2$, where  $r$ is the distance from the centre ; $a$ and $b$ are constants. Then, the charge density inside the ball is :

Which of the following is true for the figure showing electric lines of force? ($E$ is electrical field, $V$ is potential)

The electric potential at a point $(x,\;y)$ in the $x – y$ plane is given by $V = – kxy$. The field intensity at a distance $r$ from the origin varies as

The potential (in volts ) of a charge distribution is given by

$V(z)\, = \,30 – 5{z^2}for\,\left| z \right| \le 1\,m$

$V(z)\, = \,35 – 10\,\left| z \right|for\,\left| z \right| \ge 1\,m$

$V(z)$  does not depend on $x$  and  $y.$  If this potential is generated by a constant charge per unit volume $\rho _0$ (in units of $\varepsilon _0$ ) which is spread over a certain region, then choose the correct statement

For a charged spherical ball, electrostatic potential inside the ball varies with $r$ as $V =2 ar ^2+ b$. Here, $a$ and $b$ are constant and $r$ is the distance from the center. The volume charge density inside the ball is $-\lambda a \varepsilon$. The value of $\lambda$ is $………..$. $\varepsilon=$ permittivity of medium.