Magnetic Needle Behavior?

I assume these were the plastic encapsulated stirring magnets used in chem labs.
Magnetic poles at opposite ends.

Weigh each one with N pole upward. The scale or balance should show a minimum difference. Then each one with S pole upward. The two should show a minimum difference from each other.

The difference in readings for the N up vs S up is due the attraction or repulsion of the earth's magnetic field.

When the two are placed together the magnetic flux is shorted between them and they are then NOT affected by external, read the earth's, magnetic field.

Hello nandan, The anomilies you are observing may be easily explained if you are using electronic scales. First check for screening as any magnetic or electrostatic fields will cause errors.

The magnetic field of the Earth should not effect the weight. The magnets are probably interacting with the structure of the scale. Try using a small cardboard box to space the magnet(s) away from the scale. The weights should be consistent then.

Bap.

It sounds as if Guest is correct about the cause - there is something else that is magnetic that is reacting with your stirrers. It could be as simple as a pair of scissors or a metallic bench nearby that is magnetised by the Earth's field. Or it could be that someone has used NiCD or other magnetically active batteries as the power source for the scales - once you have eliminated other causes, changing to Zn-Carbon might help. The actual electronic balances SHOULD not be affected by (relatively) time invariant fields of the stirrers, but this doesn't mean that everything that is called precision actually meets this requirement.

Fyz