Iron Man 1: “Reading” a magnetic strip

Posted by on July 31, 2011

I like iron so much that I spent 2.5 years studying it in grad school, so when we started seeing experiments that utilized powdered magnetite (Fe3O4) I knew we had to come up with a series. That we created an entire “series” was necessary mostly to justify our Amazon purchase of 5-pounds of powdered magnetite.


Iron Man 1 (queue music) requires:

  • 1 sheet of paper (old newspaper is fine)
  • 1/2 tsp. powdered magnetite
  • An old card with a magnetic strip (library card, credit card, etc)



1. Set the credit card down over a clean sheet of paper. Sprinkle 1/2 tsp. of powdered magnetite over the magnetic strip.

2. Gently tap the excess powder off.

3. Angle the card into the light so that you can see the thin stripes on the strip:



Why it works: 

  1. Cards with a magnetic stripe store data in magnetic particles.
  2. Magnets in the magnetic strip attract iron, and
  3. There is plenty of iron in Magnetite – Fe3O4 (Which means there are 3 iron (Fe) atoms for every 4 oxygen (O) atoms).

So, your powdered magnetite will be attracted to the magnetic stripes on your magnetic strip, leaving them (just barely) visible.


Our 5 pound bag of powdered magnetite (shown here for effect):

This is what a 5 pound bag of powdered magnetite looks like.

The bag of powdered iron oxide did tell us to consult the MSDS.  For those of you who have your own source of powdered iron (there are several good options) and decide that you will brave the hazards (this is sarcasm) of powdered iron, the gist of it is to not inhale huge plumes of the stuff.

Jason got the idea for this experiment from an article on

Have fun!

One Response to Iron Man 1: “Reading” a magnetic strip

  1. Dawne Parter

    How do you get them to show up on the site, I already activated it i just can’t find a place to add it to the site itself?

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