Finding magnitude of electric field of a cylinder

[ecsx00]

Homework Statement

Homework Equations

E = 1/4(\pi \epsilon_{0}) * \frac{p}{r^2}

The Attempt at a Solution

E = 2\pir_{0} \epsilon_{0} = pl/\epsilon_{0}
= \frac{pr}{2\pi r_{0} \epsilon_{0}}

I am going by what I know about Gauss Law and using a similar format for the Electric field equation for a infinite charge line in a cylinder.

I fixed it little by little and I left off at:
E = \frac{r}{2 \epsilon_{0}}
The hint it gives me is that i am missing p but putting p in the numerator or denominator will say it is not dependent on p.
I probably did something wrong in the process or used a wrong equation.

 

[Muphrid]

What you have written is gibberish. Is this a uniformly charged cylinder?

You have to start at Gauss's law:

\oint E \cdot dA = Q_\text{enc}/\epsilon_0

And then invoke cylindrical symmetry to say that

|E|A = Q_\text{enc}/\epsilon_0

What is the area A of the Gaussian surface? What is the charge enclosed by this surface?