HowTo: See Invisible Magnetic Fields
"Magnetic fields are everywhere- you just can't see them."
The science-inspired-art project, Magnetic Movie, by Semiconductor, demonstrates the imaginary "secret lives of invisible magnetic fields". Don't miss it - it's an amazing project. The magnetic fields are beautifully depicted. However, they are indeed imaginary.
"Here we introduce some basic and inexpensive visual tools, as varied as iron filings and Arduino, pre-school toys and OpenGL, for getting to know your local fields. It's not exhaustive, but might provide you with some useful starting points for your own exploration."
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