# Calculating potential from a nonuniform linear charge distribution.

## Homework Statement

The thin plastic rod has length L, and a nonuniform linear charge density λ = cx. With V = 0 at infinity, find the electric potential (in V) at point P1 on the axis, at distance d from one end.
c = 28.9 pC/m^2
L = 12.0cm
d = 3.00 cm

Now, from what I can tell the left side of the rod is placed at the origin, and p1 is a distance of d from the left end.

## Homework Equations

V = (kq)/r (potential of the point charge).

$V = \int \frac{kcx}{x+d} dx$.

k is the Coulomb constant.

## The Attempt at a Solution

Now I assumed using the above equation to integrate the potential over 0 to L would give the solution. However, when I checked the back of the book I was mistaken. Is it possible I missed something? I am treating cx dx as an point charge and summing over the potential each one produces at the point in question.

I get using the equation 156Volts while the book claims the answer to be 18.6mV.