Force on a point charge near a uniformly charged rod

[athenad07]

Homework Statement

The charge per unit length on the thin rod shown here is What is the electric force on the point charge q? (See the preceding problem.)

Relevant Equations

here are the solution that I calculated, and I use the equation that E field equal to Force among charges over charges, but it yield quit different answer than the correct answer.

 

[kuruman]

This equation is set up incorrectly.

1. You are confusing the constant length of the rod $l$ with the variable of integration $x$. You should keep the two separate and rewrite the integral.
2. You want to add contributions from the entire rod, so the lower limit should be at the left end of the rod.

We would appreciate if you used LaTeX to post equations. To learn how, click on the link "LaTwX Guide", lower left, just above "Attach files."

(Edited for typos.)

 

[athenad07]

Okay! I will next time, thank you for the advice. Seems I still have a long way to learn :)

 

[kuruman]

Okay! I will next time, thank you for the advice. Seems I still have a long way to learn :)

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