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

The time for the capacitor voltage to fall to 20 v, A capacitor is charged ...

A capacitor is charged to 100 V and then discharged by a 50 kΩ resistor. If the time constant of the circuit is 0.8 s, verify: (a)  The value of the capacitor, (b)  The time

What are the important requirements of a insulating material, What are the ...

What are the important requirements of a good insulating material? Important requirements of good insulating materials:- The necessity of good insulating materials can be cl

Characteristics of common source amplifier, Characteristics of Common Sou...

Characteristics of Common Source Amplifier At low frequencies and by using a simplified hybrid-pi model, the following small-signal characteristics can be derived.

Ani immediate with accumulator instruction , ANI AND Immediate  with Accum...

ANI AND Immediate  with Accumulator Instruction 8 bit  data specified  in the  instruction is logically  AND with the  contents  of the  accumulator. The result is stored  in

Piezo crystal osillator, whether piezo crystal and quazt crystal oscillator...

whether piezo crystal and quazt crystal oscillator are same?

Explain electric polarization, Explain electric polarization. Electr...

Explain electric polarization. Electric polarization : This polarization density is the vector field such expresses the density of permanent or induced electric dipole momen

Rectifiers - Rectifiers and inverters , Rectifiers As discussed  above...

Rectifiers As discussed  above the  purpose  of the  rectifier is to  convert the incoming  ac from a transformer or other ac  source  to some  form of  pulsating dc. That it i

What is a co-processor, What is a co-processor? 8087 NDP (numerical da...

What is a co-processor? 8087 NDP (numerical data processor) is also termed as math co-processor that is used in parallel with the major processor for number crunching applicat

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