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

Surge current - thyristor, Surge Current It is  the maximum admissib...

Surge Current It is  the maximum admissible peak value of  a sinusoidal half  cycle of 10 ms duration at a frequency of 50Hz. The  value is specified at a given junction tem

What are the various tones used in stronger telephony, Q. What are the vari...

Q. What are the various tones used in stronger telephony? When called party line is obtained, exchange control equipment transmits out the ringing current to telephone set of t

What is meant by biasing transistor, Q. What is meant by biasing transistor...

Q. What is meant by biasing transistor? The purpose of dc biasing of transistor is to obtain a certain dc collector current at a certain dc collector voltage. These values of c

Determine the advantages of e-nrz over nrz, 1. A modi?ed NRZ code known as ...

1. A modi?ed NRZ code known as enhanced-NRZ (E-NRZ) operates on 7-bit words; invert- ing bits 2,3,6 and 7; and adding one parity bit to each word. The parity bit is chosen to make

Fiind the magnitudes of the line-to-line voltages, Q. A single-line diagram...

Q. A single-line diagram of a three-phase transformer bank connected to a load is given in Figure. Find the magnitudes of the line-to-line voltages, line currents, phase voltages,

Chemistry, Write short note on hardness of water and its units

Write short note on hardness of water and its units

Explain about address structure, Q. Explain about Address Structure? A...

Q. Explain about Address Structure? Address Structure: ISDN address structure is illustrated in figure. ISDN number part has a maximum of 15 digits and ISDN sub address part

Matlab, design analog normalised low pass filter by using matlab routine ch...

design analog normalised low pass filter by using matlab routine cheb1ap

The time constant of the circuit, A 20µF capacitor is connected in series w...

A 20µF capacitor is connected in series with a 50 kΩ resistor and the circuit is connected to a 20 V, d.c. supply. Verify: a)  The initial value of the current flowing, b)  T

What is interfacing, What is interfacing? An interface is a shared boun...

What is interfacing? An interface is a shared boundary among the devices which includes sharing information. Interfacing is the process of making two dissimilar systems communi

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