What is the source of the magnetic field inside the box?

AI Thread Summary
The discussion revolves around identifying the source of the magnetic field within a box, referencing Gauss's Law for Magnetism. The initial analysis rules out a bar magnet and magnetic monopoles due to incorrect field direction and flux considerations. The conclusion indicates that a current-carrying coil inside the box is the correct source, as it generates a non-zero magnetic flux. However, it is emphasized that while the coil creates a magnetic field, it does not act as a magnetic source in the traditional sense, as it adheres to the condition div(B) = 0. The conversation highlights the complexities of magnetic field sources and the implications of current flow on magnetic flux.
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Question:
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Formula: (Gauss's Law for Magnetism)
Line integral of[B dot nhat(perpendicular unit vector) * deltaA] = 0

The Attempt at a Solution


So, if there is a bar magnet inside, the side arrows are pointing in the wrong direction, so I ruled that out.

A magnetic monopole will have all arrows emanating from the center or all pointing towards the center, so I ruled that out.

The total flux is not 0, so there has to be something in it?

->That left me with only 2 other choices, but I've tried all combinations of them and none of them are correct. Any help guys? I only have 2 more tries left and its due tomorrow...

Thanks alot!
 
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The fourth choice is correct, because if you keep a current carrying coil inside it will also have the lines of magnetic fields entering and leaving.
 
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The flux through the box is nonzero. You are right, there is 'something' inside it. If you believe the flux. But we know of no magnetic sources (i.e. monopoles). And a current carrying wire is NOT A SOURCE. It has div(B)=0. Conclusion?
 
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