You’ve probably heard the term magnetic gradient before, but have you ever seen one? Now you can in [supermagnetman’s] video, below. The key is to use very fine (2 micron) iron filings and special ...

You’ve seen the pattern in science class when you laid bits of iron around a bar magnet. The invisible force field around the magnet becomes suddenly visible when the iron filings fall into line.

When you demonstrate the magnetic field of a bar magnet using iron filings, the filings form lines. But isn’t the field a continuous plane? What makes the lines form and why do they spread apart at ...