alleryStart learning →Why can a ferromagnetic coating store digital information on a hard drive?
AThe coating loses all poles when written
BThe coating conducts current only one way
CSmall domains can be reversed or erased
DSmall domains cannot be changed at all
Answer & Solution
Correct answer: C. Small domains can be reversed or erased
1. A ferromagnetic coating is divided into small domains, each with its own field orientation.
2. An electromagnet can reverse or erase the orientation of those domains.
3. A region is then either magnetic or not, which is exactly what digital storage needs.
4. Domains that could not be changed would hold no writable information.
5. Magnetic storage on videotapes and computer hard drives works on this principle.
_Source: OpenStax College Physics (CC BY 4.0), Ch 22 "Magnetism", section 22.2 Ferromagnets and Electromagnets_
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