Soft iron in magnets?

Question

If soft iron is a very poor material for permenant magnets, why is it when the same material is oxidised into ferrite dust it can be sprinkled on to cellotape where it performs well as a permenant magnet for storing intelligence, similar to casset tape, and depite being coiled does not lose its permabillity, I have been playing around with magnets for fifty years, and have more questions than answers

Many thanks for taking the time and interest to answer but I think your answer is more related to computers,if you put a new cassete in a recorder and the magnetism was random: you would get an allmighty back noise when switched to play, a recorder has an ocillater running the first head to erase or (degausse) the tape this takes more current than the amplifier, 60 years ago they used to bring a miniture horse shoe magnet against the tape to polorise it in one direction. if miniture magnets were lumped together, as you describe they would form one big magnet, like proverbial (theres a hole in my bucket dear Lisa) lump of soft iron

Answer 1

Ferrite dust particles (iron oxide) is not the same as soft iron. Ferrite dust is like tiny permanent magnets that act as bar magnets and can be aligned by a recording head to follow sound patterns (as in a tape recorder). The recording process aligns all the N/S poles according to the modulating wave pattern. When a recording is erased, the little bar magnets are not de-magnetised, just randomised. Hope this helps.