Question

Which of the following statements is not correct regarding ferrites?
1. Ferrites, with large magnetostrictive effects, are used in electromechanical transducers.
2. Ferrites have very high resistivity.
3. Hard magnetic ferrites are used for the manufacture of light weight permanent magnetis.
4. Soft magnetic materials can be used for making permanent magnets.

Answer 1

Correct Answer - Option 4 : Soft magnetic materials can be used for making permanent magnets.

Ferrites:

Ferrite is a ceramic-like material with magnetic properties that are useful in many types of electronic devices. Ferrites are hard, brittle, and iron-containing.

A ferrite is usually described by the formula M (Fex Oy), where M represents any metal that forms divalent bonds.

Magnetic properties:

• Ferrites exhibit a form of magnetism called Ferrimagnetism, which is distinguished from the ferromagnetism of such materials as iron, cobalt, and nickel.
• The most important properties of ferrites are high magnetic permeability and high electrical resistance.
• The higher magnetic materials give the B-H loop (Hysteresis loop) a large area by means of the great loss of energy.
• High magnetic materials induce the great loss of energy by means of eddy currents. This will minimize by reducing the magnetization in material and increase the resistivity of ferrites. So, Ferrites have high resistivity to get low eddy current loss.
• Hard magnetic materials can be used for making permanent magnets.
• Soft ferrites are used in high frequency transformer as they have high permeability, low coercive field, low eddy current losses and operating frequency up to 10 MHz.
• Ferrites, with large magnetostrictive effects, are used in electromechanical transducers.