A uniformly charged, straight filament 4.95 m in length has a total positive charge of 2.00 µC. An uncharged cardboard cylinder 1.65 cm in length and 10.0 cm in radius surrounds the filament at its center, with the filament as the axis of the cylinder. Using reasonable approximations, find: a. the electric field at the surface of the cylinder
b. the total electric flux through the cylinder

The electric field at the cylinder surface = 80.19 kN/C

Electric flux via the cylinder

Explanation:

Given that:

For the filament

The length = 4.95 m

The charge = 2.00  µC

The charge per unit length for the filament can be computed as:

Using Gauss's law:

---- (1)

where;

electric flux =

permittivity of free space =

electric field = E

surface area = dA

However, the electric flux via the cylinder can be expressed as:

Equation (1) can now be rewritten as:

replacing the values into the above equation:

Thus, the electric field at the cylinder surface = 80.19 kN/C

The electric flux now is calculated using the said formula:

i don't know that i agree with that but what's the question ?