Question

Which of the following is used to make permanent magnets?
A) Soft iron
B) Steel
C) Nichrome
D) Copper

Answer 1

Hint: More the ferromagnetic nature of an element the better its magnetic nature. Most ferromagnetic elements are metals. Metals of great ferromagnetic nature have a greater tendency to stay as a magnet for a longer period, this property is called hysteresis. This is due to the alignment pattern of their atoms being in the same direction.

Complete step by step solution:
Out of all the metals mentioned in the question the most ferromagnetic material is steel. A soft iron does not retain its magnetism when it is put in a magnetic field which is why it is used to make electromagnets. From the remaining three materials in the question, steel can stay as a magnet for the longest time even after removing it from a magnetic field. This makes steel the best material to make permanent magnets.

Hence option (B), Steel is the correct answer.

Additional Information: Steel has one of the highest correctivity which means that it needs the most energy to demagnetize it. Also, it has a low permeability. Which is why it is most suitable for making permanent magnets. The exact opposite is required in the case of an electrostatic magnet, a high permeability and low corectivity are required.

Note: The amount of how much material is magnetized is called remanence. Although steel is used to make permanent magnets when it is placed in a magnetic field opposite to the direction of the magnetic field of the permanent steel magnet it loses its magnetic property. This is in the case of most of the permanent magnets.