Electric Charge and Electric Fields

AI Thread Summary
The discussion focuses on calculating the electric field generated by an infinite plane sheet with an excess of 2.5 X 10^6 electrons per square centimeter. The electric field magnitude at a point 5 cm from the sheet is determined to be 226 N/C directed towards the sheet. The participants clarify that the distance is negligible due to the infinite nature of the plane. The correct equation for the electric field is confirmed to be E = sigma / (2 epsilon_0), where sigma represents surface charge density. The conversation concludes with an acknowledgment of improved understanding of the concept.
aquabug918
Messages
17
Reaction score
0
Each quare centimeter of the surface of an infinite p;ane sheet of paper has 2.5 X 10^6 excess electrons. Find the magnitude and direction of the electric field at a point 5 cm from the surface of the sheet, if the sheet is large enough to be treated as an infinite plane.

This is an odd problem and the answer is:
226 N/C towards the sheet

I understant why it is towards the sheet. I am guessing that since it is an infinite plane the 5 cm distance is unimportant.

does this have something to do with the equation: E = 2*sigma / 2*Eo

Thanks!
 
Physics news on Phys.org
aquabug918 said:
Each quare centimeter of the surface of an infinite p;ane sheet of paper has 2.5 X 10^6 excess electrons. Find the magnitude and direction of the electric field at a point 5 cm from the surface of the sheet, if the sheet is large enough to be treated as an infinite plane.

This is an odd problem and the answer is:
226 N/C towards the sheet

I understant why it is towards the sheet. I am guessing that since it is an infinite plane the 5 cm distance is unimportant.

does this have something to do with the equation: E =sigma / 2*Eo

Thanks!

Yes, that's the basic idea (except that the equation is 2 sigma /(2 epsilon_0).

That's all there is to it.
(you know how to calculate sigma, I assume. Just take the number of excess electrons times the charge of one electron divided by the 1 cm^2. Don't forget that 1cm^2 = 10^(-4) m^2).

EDIT: I retyped the wrong equation by mistake. Sorry. It is of course sigma/(2 epsilon_0)

Patrick
 
Last edited:
Thanks a lot, i understand it better now!
 
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
Back
Top