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**1. Homework Statement**

what is the approx electric field 1cm above a typical sheet of paper with a surface charge density of sigma = 45 nC/m^2?

**2. Homework Equations**

electric field E = sigma/epsilon_0 where epsilon_0 = 8.85*10^-12

E = kq/r^2 where k = 9*10^9, r is distance in meters

assume paper is charged sheet, then E = sigma/2*epsilon_0

**3. The Attempt at a Solution**

i assumed that 1 cm is so small that the distance is insignificant and could be ignored, i think this is why i got it wrong. anyways...

E = sigma/epsilon_0 = (45*10^-8)/(8.85*10^-12) = 50847 N/C

it is wrong, how do i factor in the distance? should i have used the charged sheet formula instead or the general equation (the first one)?