We have derived the formula E=(lambda)/(2pi in_0 r) considering only a finite length l of the wire. How are we justified in taking the equation valid for the entire wire of infinite length?

We have derived the formula E=(lambda)/(2pi in_0 r) considering only a

1.	We have derived the formula E=(lambda)/(2pi in_0 r) considering only a finite length l of the wire. How are we justified in taking the equation valid for the entire wire of infinite length?
Answer» Solution :This is because, the TOTAL charge ENCLOSED will be `lambdaL` and total surface area will be `(2pi R)` L and L cancels out in `Eqn. E(2pi r) L=(lambdaL)/(in_0)` EVEN when l is INFINITY.