Question

Which of the following is the best material for an electromagnet's core?

• A. Air
• B. Steel
• C. Soft iron
• D. Copper-Nickel alloy

Answer 1

The correct option is C

Soft iron

Step 1: Explanation of the correct option

In the case of option C,

1. When an electric current is passed via an insulated copper wire, an electromagnet behaves like a magnet and loses its magnetism when the current is interrupted.
2. It consists of a core that is made up of a soft iron piece with an insulated copper wire wound on it.
3. When an electric current passes through the solenoid, soft iron acquires magnetic properties, and when there is no electric current, soft iron loses magnetic properties. Therefore, soft iron is chosen for the core of the electromagnet.

Step 2: Explanation for the incorrect options

In the case of option A,

The atmosphere of Earth is covered by air, which is a mixture of various gases and small dust particles.

In the case of option B,

1. Steel is more difficult to magnetize, and it is also more difficult to demagnetize.
2. If steel is chosen to make the core of an electromagnet, then after the current is turned off, the steel retains its magnetism and becomes a permanent magnet. As a result, steel is not used as the electromagnet's core.

In the case of option D

1. Copper-Nickel, often known as cupronickel is an alloy of copper that contains nickel as well as reinforcing components like iron and manganese.
2. Due to their resistance to corrosion, copper-nickel alloys are commonly utilized in naval and marine applications.

Hence, option D is the correct answer.