Find electric field a distance from a charged sheet

[rocapp]

Homework Statement

For a sheet of infinitesimal area, find the electric field 9 mm from the surface if the charge density is 5 μC/mm^2.

Homework Equations

E=σ/2ε₀

The Attempt at a Solution

E=(5x10^-6 C/m^2)/(2*8.85x10^-12)

= 2.8 x10^5N/C

I know the correct answer is about 5.6x10^11 N/C, but I'm not sure why. Probably units? I'm not sure how to get N/C at the end when I'm given microcoulombs/mm^2 to begin with. Please help! Thank in advance.

 

[ap123]

Yes, this is a problem with the units.
You need to convert σ into SI units, ie C/m²

 

[DrZoidberg]

(5C/m^2) / (2*8.85x10^-12C/Vm) = 2.82x10^11 V/m

 

[SammyS]

Homework Statement

For a sheet of infinitesimal area, find the electric field 9 mm from the surface if the charge density is 5 μC/mm^2.

Homework Equations

E=σ/2ε₀

The Attempt at a Solution

E=(5x10^-6 C/m^2)/(2*8.85x10^-12)

= 2.8 x10^5N/C

I know the correct answer is about 5.6x10^11 N/C, but I'm not sure why. Probably units? I'm not sure how to get N/C at the end when I'm given microcoulombs/mm^2 to begin with. Please help! Thank in advance.

What on Earth is a sheet of infinitesimal area ?