Knob Magnet, Neodymium

Summary

Material: standard, neodymium

Shape: round magnet on wooden knob

Size:

- magnet 20mm X 10mm

- total height including the wooden knob, 40m

Amazingly powerful for the size, nice to hold, nice to use

Strength

How many sheets of paper will this magnet hold securely onto a fridge door?

Answer: 43

The paper was 90g in weight (a good quality paper, not standard copy paper) and was A4 in size. 

Uses for testing

Gold and silver are not magnetic. So when you are presented with dozens of items to test, save time by picking out all the items that are magnetic.

This does NOT mean that there are special magnets for testing gold and silver. If an item is NOT magnetic, it could be any one of hundreds of metals (including gold and silver).

Silver is strongly 'diamagnetic'. If you slide an appropriate magnet down a flat silver surface (e.g. a coin) it will move slowly instead of 'falling off'. Copper is slightly diamagnetic. See our 'magnets for silver testing' - a set of 3 magnet, a sample copper coin and instructions.

Copper is not magnetic, neither is brass (a mixture of copper and zinc) or bronze (a mixture of copper and mostly tin). A magnet is useful because many copper / bronze / brass items are really steel that has been plated and will (in most cases) be very magnetic. As with gold and silver: if an item is magnetic it is not solid copper / bronze / brass.

Samples

Not sure which magnet to buy? We have a bargain sample pack of nine different magnets (both neodymium and iron), click here.