Question

What distinguishes hard magnetic materials from soft magnetic materials in terms of their application?

• A. Hard magnetic materials are easier to magnetize and demagnetize.
• B. Soft magnetic materials are typically used in permanent magnets.
• C. Hard magnetic materials retain their magnetism and are used in permanent magnets.
• D. Soft magnetic materials have higher coercivity than hard magnetic materials.

Hint:

Hard vs Soft Magnets. Soft Magnets: Easy to magnetize/demagnetize (low coercivity), narrow hysteresis loop, used in cores (transformers, inductors). Hard Magnets: Hard to magnetize/demagnetize (high coercivity), wide hysteresis loop, used for permanent magnets.

Answer 1

The Correct Option is C

Magnetic materials are classified as soft or hard based on their hysteresis loop characteristics: - Soft Magnetic Materials: Have low coercivity, low retentivity, and a narrow hysteresis loop.
They are easily magnetized and demagnetized with minimal energy loss.
Applications: Transformer cores, electromagnets, inductors (where flux needs to change easily).
- Hard Magnetic Materials: Have high coercivity, high retentivity, and a wide hysteresis loop.
They are difficult to magnetize and demagnetize and retain their magnetism well once magnetized.
Applications: Permanent magnets (used in motors, speakers, data storage).
Option (1) describes soft materials.
Option (2) is incorrect; soft materials are used where magnetism needs to change easily.
Option (3) correctly states that hard materials retain magnetism and are used for permanent magnets.
Option (4) is incorrect; hard materials have higher coercivity.