Line charge density of a 30µC wire 7.0m long

[tnutty]

Homework Statement

A straight wire 7.0m long carries 30uC distributed uniformly over its length.
What is the line charge density on the wire?

_____ uC/m

Homework Equations

A) E = 2k/lamda /

B) E = kq/r

some other ones?

The Attempt at a Solution

I sub B into a, and got q/2 = 15. But its not correct. Which formula do I use?

 

[PhaseShifter]

Neither.

Hint: You're given charge and length and asked to calculate charge per unit length...shouldn't be too hard to figure this one out ;)