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## Homework Statement

A flate surface with area 0.14m^2 lies in x-y plane in a uniform electric field given by E=5.1i+2.1j+3.5k kN/c

find the flux through this surface

## Homework Equations

I know that flux= EA which E and A are given so I multiply The area with the victor E but I got a wrong answer

## The Attempt at a Solution

0.14m^2(5.1i+2.1j+3.5k kN/c)=7.14e-1i+2.94e-1j+4.9e-1z

but the correct answer is 490Nm^2/C,

how come can someone please help me. thanks.

## Homework Statement

3)A 10-{ nC} point charge is located at the center of a thin spherical shell of radius 8.0 { cm} carrying -20 {{ nC}} distributed uniformly over its surface.

A.What is the magnitude of the electric field 2.0 {cm} from the point charge and the direction of the field?

B. What is the magnitude of the electric field 15 { cm} from the point charge?

## Homework Equations

E outside spherical =Q/4pi[tex]k\ =\ 1.3806503(24)\ \times\ 10^{-23}\ J\ K^{-1}[/tex]r^2

and E inside= Qr/4pi[tex]k\ =\ 1.3806503(24)\ \times\ 10^{-23}\ J\ K^{-1}[/tex]r^3

## The Attempt at a Solution

R^3A)and since 8.0cm>2.0cm it's outside so I used the outside equation

(10e19)(2e-2)/(4pi(9e-2)(8e2^3)=3.45e3

but the correct answer is 230kN/C

b) since 15cm>8.0cm the E is inside therefore

(.08)/4pi(9e-12)(.15)=4.19.e3

but my answer is wrong

## Homework Statement

2)A sock comes out of the dryer with 10^12 excess electron.

What's the electric flux through a surface surrounding the socks?

## Homework Equations

Flux= EA

but since the area was not given

flux= Q

_{enclosed}?[tex]k\ =\ 1.3806503(24)\ \times\ 10^{-23}\ J\ K^{-1}[/tex]

## The Attempt at a Solution

10^12.9e-12=1.e23

but correct answer is 1.18e4Nm^2/C

please help me because I have a test on flux tomorrow and without understanding this might cause me. thanks.