- #1
katta002
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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= Qenclosed?[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.