# Charge Q is distributed uniformly over a thin rod

Evelima
Charge Q is distributed uniformly over a thin rod....

## Homework Statement

Charge Q is distributed uniformly over a thin rod of
lying along the x-axis between points (a,0) and (b,0)
questions.

a) What is the linear charge density on the rod?
b) Find the electric field at the origin.

## Homework Equations

linear charge density = Q / l
E = k Q / rˆ2

## The Attempt at a Solution

This is what I got so far ...

dQ = lambda*dx = Qdx/(b-a)

integral of E = k dQ/rˆ2 i
= integral from a to b of k*lambda*dx/xˆ2 = k*lambda*(-1/b+1/a)

## The Attempt at a Solution

Homework Helper

Looks good. You get a nicer looking answer for b if you drop the lambda and express it in terms of the given Q, a and b. Get a common denominator for that nasty 1/a - 1/b.

Gold Member

yes, just proceed and replace lambda.