Ferromagnetic materials-

materials which exhibit a spontaneous net magnetization at the atomic level, even in the absence of an external magnetic field.

Explanation:

When a material is placed within a magnetic field, the magnetic forces of the material's electrons will be affected. This effect is known as Faraday's Law of Magnetic Induction. However, materials can react quite differently to the presence of an external magnetic field. This reaction is dependent on a number of factors, such as the atomic and molecular structure of the material, and the net magnetic field associated with the atoms. The magnetic moments associated with atoms have three origins. These are the electron motion, the change in motion caused by an external magnetic field, and the spin of the electrons.

this could be newton#'s law of cooling. the cooling curve is exponential

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