Electric Field of a finite line of charge

[johnnyies]

Homework Statement

I just took an exam and one of the questions gave us a finite line of charge and asked us to calculate the E-field at a point at a point P to the right of the line of charge.

here is a poor sketch

[+][+][+][+][+][+][+][+][+][+][+][+]---------------------------------- .P
(thin line of charge)

now my initial thought would be that E at point P = 0, since if we drew the field lines they would point radially outward and perpendicular to the line of charge. However, 0 was not any of the available answers.

The only equation given to us was the one for a point that is in the perpendicular bisector of the line of charge, which cannot apply in this case. How would we go about solving this?

Homework Equations

The Attempt at a Solution

 

[Spinnor]

You wrote,

"now my initial thought would be that E at point P = 0, since if we drew the field lines they would point radially outward and perpendicular to the line of charge. However, 0 was not any of the available."

I think that is true only for an infinite line of charge. I think you could divide the line of charge into small elements and add the electric field at point P due to all the elements of charge?