Homework Help: Magnetic Flux through a hemisphere.

1. The problem statement, all variables and given/known data
Symbolic question:
Consider the hemispherical closed surface in Figure P30.34. The hemisphere is in a uniform magnetic field that makes an angle θ with the vertical.

(a) Calculate the magnetic flux through the flat surface (S1), using pi for π, theta for θ, B, and R as necessary.
(b) Calculate the magnetic flux through the hemispherical surface (S2), using pi for π, theta for θ, B, and R as necessary.

2. Relevant equations
Magnetic Flux =
[Surface integral](B (dot) dA)
(My apologies for...not knowing how to insert equations yet)

3. The attempt at a solution
Well, the problem states the magnetic field is uniform, so, at least for the flat surface, I should be able to pull the "B" out of the integral, as well as the cos(theta) so, you are left with Bcos(theta)piR^(2), (the area of surface one). Yet it is incorrect. For part b, I would assume it would be the same as part a, seeing as how it is a surface integral. (If my concept of surface integrals are correct)

 

My apology for that.

Well, for part (a) I have tried my answer, yet, it is still wrong, and yes I have checked to make sure it was typed in correctly.
For part (b) I believe it only wants the flux for the surface of two, so it is not closed with out surface one, because zero was the incorrect answer as well.

 

Ah, so the magnetic flux for the second surface is just the negative of the first surface? Yet, if that is the case...I still cannot obtain the correct answer for part (a).
This is exactly what I typed in the answer box.
cos(theta)*B*pi*R^2
And I looked at the preview of the answer..and everything seems to be okay.
It is still incorrect.

 

Yup, you were right, I had to switch them...yet, I am still clueless as to why... But thank you for your help!