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

Traffic light display, Traffic Light Display Design a three color LED sy...

Traffic Light Display Design a three color LED system with the following times for each LED: Duration of Green signal : 16s Duration of Yellow signal : 1s Duration of R

Power supply and clock frequency - pins and signals , Power Supply  and C...

Power Supply  and Clock Frequency there are following  pins  for power  supply  and clock  frequency  signals. V CC + 5 V  power supply. V SS Ground reference X 1

Find the turns ratio, Q A60-Hz, 100-kVA, 2400/240-V(rms) transformer is use...

Q A60-Hz, 100-kVA, 2400/240-V(rms) transformer is used as a step-down transformer from a transmission line to a distribution system. Consider the transformer to be ideal. (a) Fi

N-type semiconductor, a)  Sketch the variation of electron concentration wi...

a)  Sketch the variation of electron concentration with temperature for i)  an n-type semiconductor doped with 1021  donors m-3 ii)  an intrinsic semiconductor.  b)  Expla

What are the predefined interrupts in 8086, What are the predefined interru...

What are the predefined interrupts in 8086? The predefined interrupts are, DIVISION BY ZERO (type 0) Interrupt. SINGLE STEP (type 1) Interrupt. NONMASKABLE (ty

What is meant by microcontroller, What is meant by microcontroller? A d...

What is meant by microcontroller? A device which having the microprocessor with integrated peripherals like memory, serial ports, parallel ports, timer/counter, interrupt contr

Draw and explain the circuit of wein bridge oscillator, Q. Draw and explain...

Q. Draw and explain the circuit of Wein bridge oscillator. Obtain the expressions for the (i) frequency of oscillation and (ii) condition for oscillation. Will oscillat

How to connect the coil to the supply, A coil has an inductance of 1.2H and...

A coil has an inductance of 1.2H and a resistance of 40? and is connected to a 200 V, d.c. supply. Verify the approximate value of the current flowing 60 ms after connecting the co

Why we need digital systems, Q. Why we need digital systems? EASIER TO ...

Q. Why we need digital systems? EASIER TO PROCESS: For the reason that digitized information breaks all information into discrete units the information is easier to process and

How can we prove that radio waves are sine waves, What makes them sine? ...

What makes them sine? Ans) Fourier tells that only a sine wave has no harmonic content. The math works out that if you have any wave shape other than a sign wave, you can brea

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