Calculating Net Electric Flux in a Cylindrical Solid of Charge - Homework Help

[asdf12312]

Homework Statement

The charge distribution in the figure to the right is a cylindrical solid of charge q, radius R, and length H. The Gaussian surface S is a cylindrical shell with radius r and length h, with r > R. Determine the net electric flux given that q = 12Q, R = 5L, H = 6L, r does not apply, and h = 3L (type the integer value, along with the sign, without typing units Q/e0):

Homework Equations

"The net electric flux will be in units of Q/e0, with e0 the permittivity of free space."
e0=8.85x10^-12

The Attempt at a Solution

have no idea how to do this. I tried q/e0 = 12/(8.85x10^-12) but its too huge value..maybe i got the wrong equation.

edit; i just got this. turns out you didn't need ANY equations at all, just common sense. its just q*(h/H) which in this case is 6 though I have no idea why this is the answer, it would just give you the enclosed charge right? you would still have to divide by e0..?

 

[rude man]

Homework Statement

The charge distribution in the figure to the right is a cylindrical solid of charge q, radius R, and length H. The Gaussian surface S is a cylindrical shell with radius r and length h, with r > R. Determine the net electric flux given that q = 12Q, R = 5L, H = 6L, r does not apply, and h = 3L (type the integer value, along with the sign, without typing units Q/e0):

Homework Equations

"The net electric flux will be in units of Q/e0, with e0 the permittivity of free space."
e0=8.85x10^-12

The Attempt at a Solution

have no idea how to do this. I tried q/e0 = 12/(8.85x10^-12) but its too huge value..maybe i got the wrong equation.

edit; i just got this. turns out you didn't need ANY equations at all, just common sense. its just q*(h/H) which in this case is 6 though I have no idea why this is the answer, it would just give you the enclosed charge right? you would still have to divide by e0..?

Yes the net charge inside the Gaussian surface is qh/H but substitute q = 12Q and then ε₀*(electric flux) = qh/H. The answer thus is electric flux = 12Qh/Hε₀ but the answer is to be in units of Q/ε0 so what is the answer then? Does it help if I rewrite flux = (12h/H)(Q/ε₀)?