What term describes objects that become magnetic when placed in a magnetic field?

The term that best describes objects that become magnetic when placed in a magnetic field is "induced magnets." When an object, such as a piece of iron, is introduced to a magnetic field, the magnetic field causes a realignment of the magnetic domains within the object. This realignment induces a temporary magnetism in the material, meaning that the object will exhibit magnetic properties only while it is within the magnetic field.

This phenomenon is reversible; once the external magnetic field is removed, the magnetic domains will return to their original arrangement, and the object will lose its magnetism. The term "induced magnets" specifically captures this temporary nature of magnetism caused by an external magnetic influence.

In contrast, "temporary magnets" refers to the same concept but is not the precise term used within the context of the question. "Permanent magnets" refer to materials that are magnetized and maintain their magnetism without the need for an external magnetic field. "Magnetic materials" is a broader category encompassing both permanent and induced magnets, thus it does not specifically denote the process of becoming magnetic in the presence of a magnetic field.