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

Examples of attribute data relevant for a power utility, Examples of attrib...

Examples of attribute data relevant for a power utility: Examples of attribute data relevant for a power utility are given below. •          Consumer data such as categor

Determine the transfer functions, The Ward-Leonard system, which is used in...

The Ward-Leonard system, which is used in the control of large dc motors employed in rolling mills, is a highly flexible arrangement for effecting position and speed control of a s

Variable frequency systems , Variable Frequency  Systems In this  sys...

Variable Frequency  Systems In this  systems the chopping period  T will varying but  either Ton is kept constant or T off kept constant. In  any case the off  time T off   w

Problem on pulse code modulation, (a) "Pulse Code Modulation (PCM), as used...

(a) "Pulse Code Modulation (PCM), as used in telephony, samples a signal at 8 kHz using 256 quantization levels". i. Outline how this scheme works with the help of sketches and,

Write some disadvantages of loosely coupled systems, Write some disadvantag...

Write some disadvantages of loosely coupled systems More complicated due to the needed additional communication hardware. They are less portable and more expensive because o

Describe the time division switching, Q. Describe the time division switchi...

Q. Describe the time division switching? Ans: Space and Time Switching: Space Switches: Connections can be made between outgoing and incoming PCM highways by means of

Explain effect of frequency of applied electric field, Explain effect of fr...

Explain effect of frequency of applied electric field. If an external electric field is applied, the distance among charges that is related to chemical bonding keeps constant i

Semiconductor diode, Semiconductor Diode: the semi conductor diode is ...

Semiconductor Diode: the semi conductor diode is formed by simply bringing n and p tripe material together (constructed from same base ge and si), at the instant the two mater

Explain bandwidth and applications of rc coupled amplifier, Q. Explain the ...

Q. Explain the bandwidth for the curve and the applications of an RC coupled amplifier. Frequency response curve of an RC coupled amplifier was shown above(prev page). The cut

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