Question

The properties required for a material to be used as the core of an electromagnet are:

• A. High permeability and high retentivity
• B. Low permeability and low retentivity
• C. High permeability and low retentivity
• D. Low permeability and high retentivity

Hint:

High permeability → core magnetizes easily.
Low retentivity → loses magnetism quickly when current stops.
Avoid materials like steel for electromagnet cores; they have high retentivity.
Soft iron is ideal for electromagnet cores.

Answer 1

The Correct Option is C

• For a strong electromagnet, the core should easily magnetize under applied current; this requires high magnetic permeability.
• The core should also demagnetize quickly when the current is turned off; this requires low retentivity to avoid residual magnetism.
• Materials like soft iron satisfy both conditions.
• Hence correct choice: High permeability and low retentivity.