WAEC - Physics (2024 - No. 44)
In storing magnets, the keeper is used to
cancel the effect of the earth's magnetism
reduce self demagnetization
protect the magnet from stray electric field
increase the strength of the magnet.
Explication
Keepers reduce self-demagnetization of magnets by providing a low reluctance path for magnetic flux, thereby containing the flux within the keeper.