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## Homework Statement

A cylinder of radius

**R**= cm 1.2 and length

**L**= 51 cm has a charge

**Q**=2.3 μC spread uniformly along its surface (and not on its flat ends).

a) Calculate the electric field strength a distance

**d**=4 mm from the cylinder’s surface (not near either end)

b)Calculate the electric field strength a distance

**D**=24 m from the rod

## Homework Equations

E= kQ/r^2

Surface area of cylinder without faces = 2πrL

Volume of cylinder = πr

^{2}L

pr/(2ε

_{°}) = E

## The Attempt at a Solution

My grade 12 teacher never taught us electricity so to lightly put it - I'm screwed (so please bare with me and anything I'm misunderstanding)

if my point charge is

**d**=4 mm from the cylinder then from the CENTER it is actually R+

**d**distance away. (similarly, R+

**D**distance for part b).

Now, I know I don't need to do any integration as the charge is spread uniformly along the surface.

This is where I'm not sure what to do. I know that the surface area of the cylinder without its ends is 2π

**RL,**which is the surface that the charge covers. Do I divide Q by the surface area? or do I find volume and do I create my "Gaussian surface" ie, a cylinder and use the radius R+

**d**or R+

**D**instead of

**R**to find the volume? I don't know where to go from here, if someone could explain this, and some of the physics behind it, it might help clear this up for me for good.

Thank you!