Asteel
Balnico
Csoft iron
Dcopper
Answer:
C. soft iron
Read Explanation:
The most suitable substance for the core of an electromagnet is (C) soft iron.
Explanation
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Its strength can be easily changed by varying the current. The core of an electromagnet needs to be a material that can be easily magnetized and demagnetized.
Soft iron is the ideal choice because it has very high magnetic permeability and low retentivity.
High magnetic permeability means it can be strongly magnetized even with a small external magnetic field. This allows the electromagnet to become very strong.
Low retentivity means it loses its magnetism almost completely when the electric current is turned off. This is crucial for an electromagnet, as it needs to be able to be "switched off" and not retain a permanent magnetic field.
Steel and alnico (an alloy of iron, aluminum, nickel, and cobalt) are not suitable for the core of an electromagnet. They are used to make permanent magnets because they have high retentivity, meaning they remain magnetized even after the external magnetic field is removed. This property would make it difficult to "turn off" the electromagnet.
Copper is a good conductor of electricity but it is a non-magnetic material. It cannot be used to create a magnetic field in this way.