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

How can a jfet be used as a constant current source, Q. How can a JFET be u...

Q. How can a JFET be used as a constant current source? Explain from the drain characteristics. As the VDS voltage is increased from 0 to a few volts, the current will increase

Give the operating modes of 8259a, Give the operating modes of 8259a? (...

Give the operating modes of 8259a? (a) Automatic Rotation (b) End of Interrupt (EOI) (c) Fully Nested Mode  (d) Automatic EOI Mode (e) Specific Rotation (f) Edge

What do you mean by phase sequence, Q. What do you mean by Phase Sequence? ...

Q. What do you mean by Phase Sequence? It is standard practice in the United States to designate the phase A-B-C such that under balanced conditions the voltage and current in

Different types and uses of delay line in cro, Q.   What are the different ...

Q.   What are the different types and uses of delay line in CRO? OR Why is a delay line used in the vertical section of the oscilloscope? Sol. All electronic circui

The classical free electron theory, The free electron theory of metals was ...

The free electron theory of metals was first proposed by Drude and later improved by Lorentz. The main postulates of this theory are 1.       All metal contain, adequate number

Logic Gates, A former employs a servant to look after his form house. He in...

A former employs a servant to look after his form house. He instructs the servant to keep a watch on his goat. So that he does not harm the kitchen garden, when the entrance-door

Aci add immediate with carry instruction, ACI  Add Immediate with Carry  ...

ACI  Add Immediate with Carry  Instruction Similar  to ADC instruction 8 bit  data specified  in the  instruction and Carry  are added to the contents  of the  accumulator and

Determine the thevenin resistance, Q. Determine the Thevenin resistance vie...

Q. Determine the Thevenin resistance viewed from terminals A-B of the circuit of Figure by setting independent sources to be zero and applying a test voltage at terminals A-B.

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