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

Determine the parameters of the equivalent circuit, No-load and blocked-rot...

No-load and blocked-rotor tests are conducted on a three-phase,wye-connected inductionmotor with the following results. The line-to-line voltage, line current, and total input powe

Calculate the diameter of an air-filled circular waveguide, Q. Calculate th...

Q. Calculate the diameter of an air-filled circular waveguide? Unlike transmission lines, which operate at any frequency up to a cutoff value, waveguides have both upper and lo

Find the value of noncoherent source, If E b /N 0 = 20 in a coherent ASK s...

If E b /N 0 = 20 in a coherent ASK system, find the value of Eb/N0 that is needed in a noncoherent ASK system to yield the same value of Pe as the coherent system.

Draw a 100 line exchange, Q. Draw a 100 line exchange using two motion sele...

Q. Draw a 100 line exchange using two motion selectors and elucidate, how switching takes place in it. Ans: In a 100 line exchange, every subscriber is assigned a 2 digit

Execute a pspice program to solve for the node voltages, Q. For the circuit...

Q. For the circuit given in Figure, develop and execute a PSpice program to solve for the node voltages.

Circuit theorems, limitations and applications of following circuit theorem...

limitations and applications of following circuit theorems: telleans theorem superposition theorem norton theorem compensation theorem millman theorem reciprocity theorem maximum p

3 phase 4 wire meters, 3 Phase 4 Wire Meters 3-phase 4 wire meters (10...

3 Phase 4 Wire Meters 3-phase 4 wire meters (10/20, 20/50 A) are used for agricultural and industrial consumers. For loads up to 50 A, the meters are directly linked to the su

Which stack is used in 8086, FIFO (First in First Out) stack is used in 808...

FIFO (First in First Out) stack is used in 8086.In this type of Stack the first stored information is retrieved first.

Briefly explain single mode and multimode fibres, Briefly explain single mo...

Briefly explain single mode and multimode fibres The optical fibres were categorized within two according to the number of modes it passes as: • Single mode fibres • Multi mode

Automatic frequency control , Discuss the requirement for automatic gain co...

Discuss the requirement for automatic gain control in AM receiver and automatic frequency control in FM. How are these 'control' voltage formed and used?

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