Permanent magnets, Electrical Engineering

Assignment Help:

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.

 


Related Discussions:- Permanent magnets

Explain topology method used in lan technology, Q. Explain topology method ...

Q. Explain topology method used in LAN technology? Ans: LAN Topologies: Network topology is a physical schematic which demonstrates interconnection of the many users. Th

Mr. Davis, The new kitchen is to be 20feet long and it''s width is 75% of i...

The new kitchen is to be 20feet long and it''s width is 75% of it''s length. The door to the kitchen is on the short wall and is 10% of the width of that wall. you want to put in m

Illustrate frequency-shift keying, Q. Illustrate Frequency-shift keying? ...

Q. Illustrate Frequency-shift keying? Digital transmission by FSK is a nonlinear modulation method that is appropriate for channels that lack the phase stability needed to perf

Power distribution, Determine the current through each parallel branch of t...

Determine the current through each parallel branch of the system

Determine the resultant line current and power factor, Q. A three-phase loa...

Q. A three-phase load, connected to a 440-V bus, draws 120 kWat a power factor of 0.85 lagging. In parallel with this load is a three-phase capacitor bank that is rated 50 kVAR . D

Common-drain jfet amplifier, Q. Common-Drain JFET Amplifier? Figure (a)...

Q. Common-Drain JFET Amplifier? Figure (a) shows a CD JFET amplifier in which resistors R 1 , R 2 , and R SS are selected by the bias design, and capacitors CG and CS are chos

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd