Question

Magnetisation of an iron piece is an:
A. physical change
B. chemical change
C. both A and B
D. none of these

Answer 1

Hint: Magnetization, also termed as polarization of the magnet, could be a vector quantity by which the density of permanent or induced moment during a given magnetic material can be measured.

Complete Solution :
Magnetization may be a measure of the density of magnetism and will be calculated from the amount of magnetic moments during a given volume. ... this could be shown as M = Nm/V where M is that the magnetization, N is that the quantity of the moment of a magnet, m is its direction and V is that the volume of the sample.
- The magnetic induction defines the forces that the poles of a magnet experience in an exceedingly flux whereas the intensity of magnetization explains the change within the torsion of a magnet per unit volume.
- Magnetism is caused by the motion of electrical charges. Every substance is formed from tiny units called atoms. In substances like iron, cobalt, and nickel, most of the electrons spin within the same direction. This makes the atoms in these substances strongly magnetic—but they're not yet magnets.
The M-field has a unit of amperes per meter ($A\,{{m}^{-1}}$) in SI units.
- Magnetization of iron could be a physical change and not a natural process as there's no change of state, no change of temperature, no smell and no evolution of gas. it's because: - No action is involved. - After demagnetizing the iron it'll lose its magnetic power.
So, the correct answer is “Option A”.

Note: Stroke a magnet in one direction along your object within the area you want to magnetize. This may align the domains of the fabric within the same direction. Continue rubbing within the same direction, within the same area. don't rub within the wrong way.