Question

There is an infinitely long straight thread carrying a charge with linear density λ = 0.40 μC/m. Calculate the potential difference between points 1 and 2 if point 2 is removed it η = 2.0 times farther from the thread than point 1.

Answer 1

We know from Gauss theorem that the electric field due to an infinietly long straight wire, at a perpendicular distance r from it equals, 

So, the work done is

(where x is perpendicular distance from the thread by which point 1 is removed from it.) 

Hence