For the given electrostatic potential V(z) = kQ, the electric field along the z-axis is

The electric field (E) is related to the electrostatic potential (V) by the negative gradient of the potential. Mathematically, this relationship is expressed as

In one dimension, for a spherically symmetric charge distribution, the relationship between E and V is given by
, where r is the radial distance.
Given the electrostatic potential V(z) = kQ, where k is a constant, and Q is the total charge, we can find the electric field along the z-axis (
) as follows:
![\[E_z = -(dV)/(dz)\]](https://img.qammunity.org/2024/formulas/physics/college/cs1drrr7noeala5c8wzf8ot7gbg0o7bj2m.png)
![\[E_z = -(d)/(dz)(kQ)\]](https://img.qammunity.org/2024/formulas/physics/college/29jo076g2wsa66tx56no4jj8zxsalhmux5.png)
Since k and Q are constants, the derivative with respect to z is zero, and we have:
![\[E_z = 0\]](https://img.qammunity.org/2024/formulas/physics/college/26enxsiwzuhsai70i14rfm6yktpvlg9o74.png)
Therefore, the expression that best describes the electric field in this case is

The probable question may be:
The electrostatic potential of a certain charge distribution with a total charge Q at a distance z from the distribution is given by V(z) = k Q, where b is a constant. Which expression best describes the electric field? [hint, apply E= -VV(z)].