5 Questions
What is the main difference between an electromagnet and a permanent magnet?
A permanent magnet doesn’t require a continuous supply of electricity to maintain its magnetic field
What happens when current is passed through an electromagnet?
The material is magnetized
What is a characteristic of a permanent magnet?
The poles of a permanent magnet cannot be changed
How are the magnetic properties displayed in an electromagnet?
The strength is adjusted depending upon the amount of flow of current
What happens when magnetic properties are lost in a permanent magnet?
It becomes useless
Study Notes
- An electrical machine converts electrical power to mechanical power or vice versa through the action of a magnetic field.
- Motors convert electrical power to mechanical power, generators convert mechanical power to electrical power.
- Most practical motors and generators use magnetic fields for energy conversion.
- Types of Magnets:
- Permanent Magnets: Do not lose magnetic properties once magnetized, examples include ceramic and ferrite.
- Temporary Magnets: Can be magnetized in the presence of a magnetic field, examples include iron nails and paper-clips.
- Electromagnets: Consist of a coil of wire wrapped around an iron core, generate magnetic fields with electric current, and their strength can be adjusted.
- Comparison between Electromagnets and Permanent Magnets:
- Magnetic properties are displayed when material is magnetized for electromagnets, and permanently for permanent magnets.
- Electromagnets require a continuous supply of electricity to maintain magnetic field, whereas permanent magnets do not.
- Electromagnets are usually made of soft materials, while permanent magnets are usually made of hard materials.
- The poles of electromagnets can be altered with the flow of current, whereas those of permanent magnets cannot be changed.
Test your knowledge about electrical machines and magnetic circuits with this quiz. Topics covered include the conversion of electrical power to mechanical power, the functions of motors and generators, and the principles of magnetic circuits.
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