Question

A point particle with charge q = 15 µC is placed at a corner of a cube of edge a = 5.6 cm. What is the flux through (a) each cube face forming that corner and (b) each of the other cube faces?

Answer 1

Here is my drawing.

Answer 2

(a) is zero, I am stuck on (b)

Answer 3

@UnkleRhaukus
Are you familiar with this material. Electrostatics?

Answer 4

@skullpatrol
Are you good with electrostatics?

Answer 5

why is your cube having so many mini cubes in it? :D

Answer 6

Because, in the initial problem, the charge is on one corner of a cube, so you need to put more cubes around the original so that the charge is at the center of a larger cube.

Answer 7

this is just gauss's law,

Answer 8

I tried that,

\(\Large{\Phi=\frac{q}{\epsilon_{0}}}\)

Answer 9

the electric flux goes out in straight lines from the point,

Answer 10

ohhhww. that makes sense i guess
wow.. yea.. so now you can use gauss's law and do it

u are right.. the flux IS q/e_0
but that flux is passing through ALL those surface equally..
so its just a matter of dividing by the number of surfaces!

Answer 11

the flux through the adjoining surfaces will be zero ,
and the flux thought the other surface can be found from using symmetry,

Answer 12

Will it just be zero?

Answer 13

no no.. its not zero.. think a little man.. u are on the right path!

Answer 14

the outer surfaces will get some flux , if you look at your diagram count all the outer surfaces , on the surrounding cubes , all the flux must go through these

Answer 15

4 cubes, with 6 sides each?
And don't count those sides that are along the line of the flux.

Answer 16

So... flux through 20 different cube sides?

Answer 17

24 different sides*

Answer 18

there are more than 4 cubes, but yes 24 different sides,

Answer 19

correct 24 sides!!

Answer 20

i give u medal.. cause this was an awesome problem.. !!!!

Answer 21

glad i saw this :D :D!!

Answer 22

so what is the total flux? and what portion of this flux goes thought each of those sides?

Answer 23

Okay, sorry about that. Having computer issues.

\(\Large{\Phi_{total}=175,439}\)
\(\Large{\Phi_{surfaces}=7,309.94}\)

But that doesn't seem correct.

Answer 24

are you sure u did that right? :P

Answer 25

i get 70590 Nm^2/C as the answer!

Answer 26

For the first part I have,

\(\Large{\Phi=\frac{1.5\times10^{-6}}{8.55\times10^{-12}}=175,439}\)

\(\Large{\frac{\Phi}{24}=7309.94}\)

Now, it says that it is wrong. What did I do wrong?

Answer 27

epsilon zero = 8.854 * 10^-12 Farads/ meter!

Answer 28

*facepalm*
Thank you.

Answer 29

Also.. its 15 micro
NOT 1.5 micro..

Answer 30

don't *facepalm* u need ur glasses i guess :D :D jk!