# Find y-component of Electric Field!

## Homework Statement

A plane of charge lies in the xz-plane at the origin. Its surface charge density is =4.57 uC/m^2; other charges are present in the vicinity as well. Just to the right of the origin the y-component of the electric field is 520,000N/C. What is the y-component of the electric field just to the left of the origin. Answer must take into account direction of field (left negative, right positive).

Eright = 520000
σ = 4.57 uC/m^2

## Homework Equations

Enet = σ/ 2 ε0
Enet = Eright + Eleft

## The Attempt at a Solution

I started with Enet = σ/ 2 ε0 = 258070
Eright = 520000
so via Algebra, Eleft = -261930

The sum of Eleft and Eright should be 258070,
what am I doing wrong?

Thanks...

Last edited:

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BruceW
Homework Helper
yo, erik welcome to physicsforums

I don't really understand the question. There is a plane of charge in the xz plane, going through the origin. OK, and just to the right of the origin, the y-component of the electric field is 520,000N/C I'm guessing that means the y direction is to the right?

You've got the equation Enet = σ/ 2 ε0 I don't know why you've called it Enet, because this equation tells you the magnitude of the electric field on either side of a plane of charge.

And you've got roughly the right answer for σ/ 2 ε0 = 258070 the magnitude of the electric field on either side of the plane of charge. But this doesn't make sense to me already, because this is in conflict with 520,000N/C as the value of the electric field.