Knob Magnet, Neodymium
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- Unit price
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(Single item price excluding VAT: £10.42)
Stock: Available
Pickup available from Quicktest (WD18 8JA)
Email us
or call on 01923-220206 for appointment.
Summary
Material: standard, neodymium
Shape: round magnet on wooden knob
Size:
- magnet 20mm X 10mm
- total height including the wooden knob, 40mm
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.
QUESTIONS & ANSWERS
Ask a Question-
I’m looking for a magnet to test gold and silver bars, most will be in there original assay packaging, range would be from 1gram bar to 1oz bar so the small 1g bars are only about 10mm long usually, can you recommend which magnet you have for this please
For finding non-gold, see the best magnets for large items (e.g. the size of gold bars).
But it is important to know that you cannot test gold using a magnet. Magnets are useful for removing items that are magnetic, because these items cannot be gold, because gold is not magnetic. There is a very useful (very short) article explaining this in more detail, Testing Precious Metals with Magnets.
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Hello I need agents to pick out 22/24 carat gold.thanks
Do you mean reagents (chemicals)? See our chemical testers.
Or if you are asking about magnets for testing gold, see the article about using magnets to test precious metals (summary: gold is not magnetic but magnets are useful for rejecting ‘not gold’).