Magnetic Viewing Paper - Featured on Hacked Gadgets

[douro20]

I'd imagine this is a servo magnet from a 5.25" floppy disk drive, looking at the pattern.

[metamaterial]

I had no clue those noises were made by something so pretty...

[douro20]

@metamaterial

Yep, it's called cogging. Every one of the "teeth" made visible by the powdered iron in the magnetic film has a north and a south pole on either side. Without this special magnetization pattern the thing would never work.

[metamaterial]

I think I get it now. The reason one would use such a complicated electromagnet to magnetize the ferrite rather than mold or mill the part to shape and use a simpler electromagnet to get the same magnetic field is that milling is crazy slow and resource-intensive, and sintering just doesn't allow such mold shapes.

[mario27121975]

Wast ist das? eine HARDDISK scheibe?

[Zakkyboy1]

Cool see whats in the magnet

[pastry1225]

magzzie, it will only show magnetically affected thigs, so most likely, the three common metals that are affected by magnets. i cant remember all 3, just iron.

[gbatime]

its iron, nickel & cobalt

[douro20]

And rhenium.

[magzzie]

nope to see what people are wearing

[girrrrrrr2]

i want some...try putting it up to 100 rare earth magnets in a flat layer see what happens!!!

[lexer101]

NICE

But wat's the use of it?

[themasterj]

To see the magnetic field.