A long charged cylinder has a linear charge density λ and is surrounded by a hollow coaxial conducting cylinder. What is the electric field in the space between the two cylinders at a radial distance r from the axis of the inner cylinder?
1. \(E=\dfrac{\lambda}{2\pi \epsilon_0 r^2},\) radially outward
2. \(E=\dfrac{\lambda}{2\pi \epsilon_0 r},\) radially outward
3. \(E=\dfrac{\lambda}{4\pi \epsilon_0 r},\) radially outward
4. \(E=0\)


 

 
The charge density of the long charged cylinder of length L and radius r is Another cylinder of the same length surrounds the previous cylinder. The radius of this cylinder is R.
Let E be the electric field produced in the space between the two cylinders.
The electric flux through the Gaussian surface is given by Gauss's theorem as, ϕ = E2πdL
Where d = Distance of a point from the common axis of the cylinders Let q be the total charge on the cylinder.
It can be written as
ϕ = E2πdL = qε0Where, q Charge on the inner sphere Of the outer cylinder
ε0 = permittivity of free space
E(2πdL)=λLϵ0E=λ2πϵ0d
Therefore, the electric field in the space between the two cylinders is λ2πϵ0d