47. Materials that retain a large part of their magnetization, after the magnetizing force is removed are considered to be permanent magnets. What characteristic of the material is responsible for this permanence?

Permanent magnets require high magnetic hysteresis to retain magnetization after the magnetizing force is removed. Magnetic hysteresis describes a material's ability to retain magnetization and resist demagnetization; high hysteresis indicates strong remanence and high coercivity, essential for permanent magnets. Ductility is a mechanical property and irrelevant to magnetic permanence.