Looking for a handy magnetic omni-directional rotation polarity identifier to determine a magnet's north or south pole? A Magnaprobe™ is indispensable in science lab magnetic field experiments. Be sure you're buying a genuine UK made Cochranes of Oxford Magnaprobe™ Mark II.
We can't name names but world renowned US National Labs buy this tool from us to test the magnetic fields around their particle accelerators & other equipment. Want the real thing? Find out how below.
Genuine UK made Magnaprobes™ are sturdy, non-contact, analog devices for demonstrating the 3D nature of magnetic fields. Beware cheap copies which will fail if you try this more than once.
One of the obvious differences is in the magnet mount. The handle/frame of the fake Magnaprobe typically weighs 15 % less (4.6 g vs 5.4 g) than the real thing. The pivots are poorly moulded (see above image) which makes the device less sensitive & inaccurate as well as less durable.
The fake Magnaprobe magnet bearings are not centered which can cause one end to sometimes catch on the plastic frame as it turns. This causes it to plot the magnetic field inaccurately - due to its being weighted more to one end.
The AlNiCo magnet in the fake Magnaprobe is shorter. The one we tested was 4mm less, 117 vs 121 mm and ~5% thinner, 3.0 vs 3.15 mm. The grade (quality) of the AlNiCo magnet is less according to tests. All these makes the fake Magnaprobe quite a bit less sensitive/responsive. A false economy all around.
Because of the many cheap copies of the Cochranes of Oxford Magnaprobe MarkII, specifications are propriety. Performance is determined by the grade of AlNiCo used in the magnet, its size & the precision of its dimensions. Further, the type of plastic & its precision of manufacture greatly impact its long term reliability.
We can say, however, that the AlNiCo bar magnet is a high grade making it very sensitive & is gimbel mounted. The handle is 3.25mm thick & virtually indestructible. You get what you pay for!