Permanent magnets, Electrical Engineering

Materials with 'hard' magnetic B/H characteristics often show a strong residual magnetism. This makes them suitable for making permanent magnets. If the ring material were magnetised, then the magnetised material itself will create a flux in the ring. No current carrying coil will be required.

1915_permanent magnets.png

 

For a permanent magnet, flux is produced by the alignment of magnetised domains within the material itself. (c.f earlier notes relating to residual magnetism in B/H curve).  In this case, the flux exists without the need for a coil, i.e. N.I = 0. Hence applying Ampere's Law results in:

 

1504_permanent magnet.png

Hence eqn 1 and the B/H curve must be simultaneously satisfied and to give the flux density and magnetic field strength in the magnetic material (and hence also the air gap)

 

1077_permanent magnet 1.png

 

 

from equation (1)  Bc/Hc=-Lc/Lgµ0         

 

which is slope of a straight line. The flux density and magnetic field in the magnetic circuit is given by the point at which eqn (1) cuts the B/H curve. Permanent magnets are widely used in transducers:- loud speakers, measuring meters, D.C. motors etc.

 

Posted Date: 8/22/2012 7:01:12 AM | Location : United States







Related Discussions:- Permanent magnets, Assignment Help, Ask Question on Permanent magnets, Get Answer, Expert's Help, Permanent magnets Discussions

Write discussion on Permanent magnets
Your posts are moderated
Related Questions
Q. Present and Future Trends in power systems? According to the Edison Electric Institute, electricity's share of U.S. primary energy was almost 36% in 1989, and it is likely t

write a short notes of thermal compansation?

Q. What effect do non-tradable goods have on PPP? Answer: The consequence is quite substantial. In 1997 the production of non-tradable goods accounted for about 55% of U.S GN

Q. How many 500-page books can be stored on a 2400-ft, 1600-BPI magnetic tape if a typewritten page contains about 2500 bytes?

Kirchoff's Current Law The total current entering a node in a circuit is equal to the total current leaving that node. A Node is a junction between two or more components.

to design wheatstone bridge

Discuss merits and demerits of Macro over procedures.  The MACRO directive informs assembler the starting of a macro which is used with ENDM directive to enclose a macro. The

Rise  Time (t r ) During  rise time voltage falls from 90% V a to 10%  where  V a where V a is the initial  anode  voltage. In terms  of current  time taken  by anode  curre

Transmission Through a LiNb0 3 Plate Examine the transmission of an unpolarized He-Ne laser beam (?o= 633 nm) normally incident on a LiNb0 3 plate (ne = 2.29, no = 2.20) of thickn

I need a simple design of above mentioned , this oscillator will be used in a wireless power transmission