Magic fence or power of inverse square?
On a walk through UC Berkeley, I came upon the following sign on a fence:
Here’s a broader view of the sign and its surroundings:
The distance from the building to the fence is about 2m (6′).
The question:
Has UCB discovered a new fence that can stop magnetic fields? Or, is this just an example of the inverse square relationship between the strength of a magnetic field and the distance from it?
Here’s the front of the building:
The building houses the Henry H. Wheeler, Jr. Brain Imaging Center.
Here’s a photo of the imaging device:
If the distance from the magnets to the outside of the building is 1.0 m, what is the relative strength of the magnetic field outside the fence (an additional 2 m away)?
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One eight the strength of the field at the wall (the square of three less the square of one). The edge of the potentially harmful zone is somewhere between the wall and the fence. Thus I don’t understand why you ask about the fence.
Don,
The point of the question is designed to be humorous: A fence can’t really stop the magnetic field, but the wording could be interpreted that way, since the strong magnetic field is “behind the fence.” This could be interpreted that there is a significant difference between being right in front of or right behind the fence.
A lot of potential here. I’m confused, though, about the second photo down, which seems to be the linchpin of this exploration. What am I looking at here?
Dan,
The second photo shows the arrangement of the fence and building. If you were to “walk into the photo” you’d reach the fence, climb over it, crawl under about 2 meters of shrub, then reach the wall of the building. Does this help?