The 120mm (5") bar magnet is great for experiments with iron filings, compasses or paperclips only ;$2.85 (buy 2 for a repulsion/attraction pair). For buy even more for big quantity discounts.
This is the ideal child safe magnet. Strong enough to pick up paper clips or do repulsion attraction but not so strong they snap together & break kids' fingers.
Bought ferrite bar magnets from Amazon that can't pick up more than a couple of paper clips? See Magnet Experiments for Kids-ours can pick up lots. Great accessories for these magnets include this simple iron filings viewer.
Two 120x22x10mm bar magnets were placed in contact with opposing poles (N:N). They were released and the repulsion distance was measured. The average of 5 trials is 52mm or slightly more than 2 inches. See video below.
|Trial 1||Trial 2||Trial 3||Trial 4||Trial 5||Average|
Forty paper clips were placed in a 500ml beaker. A single 120x22x10mm ferrite bar magnet was dipped into the beaker to pick up as many paper clips as possible. See video below.
|Type||Trial 1||Trial 2||Trial 3||Trial 4||Trial 5||Average|
|Plastic Coated Steel||19||19||12||17||20||17|
Note, there is no audio track.
Note: The bar magnets got a big boost by attaching 20x10x5mm Nd blocks at opposing faces of the bar magnets.
This really old video of a magnaprobe in action that shows how to identify a magnetic field around a bar magnet.
I ordered these magnets to use for "polarity-confirming" on unmarked small spot-magnets that I use for my hobbies and for our healthcare disk-magnets. They work perfectly in those applications and are totally suitable for our purposes. Thank You for the great product and the great deal, Indigo!
Thanks for the feedback. Always nice to hear someone has an application we never thought of. For those with more conventional educational needs, see our blog: Ferrite Bar Magnets, 3 Experiments at School/Home
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