Define the following terms: i) Magnetic flux density, ii) Reluctance, iii) Magneto-motive force, iv) Permeance.

Define the following terms: i) Magnetic flux density, ii) Reluctance, iii) Magneto-motive force, iv) Permeance.
by
retagged

1 Answer

Answer :

(i) Magnetic flux density (B): It is the magnetic flux per unit area measured at right angles to the flux path. (Its unit is weber/m2 or tesla). 


(ii) Reluctance: It is the opposition offered by magnetic path to flux. It is measured in AT/wb. 


(iii) Magnetic Motive Force (MMF): It is defined as the entity (quantity or force) that sets up or creates magnetic flux in a magnetic circuit. It is the product of the number of turns and the current in the coil (MMF = NI). Its unit is Ampere (A) OR ampere-turns 


(iv) Permeance: It is the property of magnetic circuit due to which it permits the magnetic flux to set up through it and it is reciprocal of reluctance. Permeance = 1/ Reluctance. Unit: weber/ampere.

by

Related questions

Define magnetic flux density and state its formula.

Description : Define magnetic flux density and state its formula.

Last Answer : The magnetic flux per unit area is called as magnetic flux density. Magnetic flux density is denoted by B. The formula for magnetic flux density is Weber per metre square or Tesla. Mathematically ... the unit of magnetic flux density is Weber per metre square which is also called as Tesla.

What is the SI unit for magnetic reluctance?

Description : What is the SI unit for magnetic reluctance? A) Ampere B) Ampere-turns per weber C) Henry D) None of these

Last Answer : What is the SI unit for magnetic reluctance? A) Ampere B) Ampere-turns per weber C) Henry D) None of these

Flux density formula

Description : Flux density formula

Last Answer : Flux density formula

what is the unit of flux density?

Last Answer : Flux density is denoted by B. And it is given as B = flux/ area Where, the unit of flux is Weber and unit of area is meter square. So the unit of flux density is weber per meter square which is also called as Tesla.

In an induction motor if the flux density is reduced to one-half, of its normal value then the torque will

Description : In an induction motor if the flux density is reduced to one-half, of its normal value then the torque will  (1) reduce to one-half (2) reduce to one-fourth (3) remain unchanged (4) increase four times

Last Answer : In an induction motor if the flux density is reduced.to one-half, of its normal value then the torque will reduce to one-fourth

If B is the flux density, I the length of conductor and v the velocity of conductor, then induced e.m.f. is given by?

Last Answer : If B is the flux density, I the length of conductor and v the velocity of conductor, then induced e.m.f. is given by Blv.

What is the permissible flux density in case of cold rolled grained oriented steel?

Description : What is the permissible flux density in case of cold rolled grained oriented steel?

Last Answer : The permissible flux density in case of cold rolled grained oriented steel is 1.7 Wb/m2.

Which of the following is a unit of magnetic flux?

Description : Which of the following is a unit of magnetic flux? A) Weber B) Maxwell C) Both A and B D) None of these

Last Answer : Which of the following is a unit of magnetic flux? A) Weber B) Maxwell C) Both A and B D) None of these

The property of a material which opposes the creation of magnetic flux in it is known as?

Description : The property of a material which opposes the creation of magnetic flux in it is known as?

Last Answer : The property of a material which opposes the creation of magnetic flux in it is known as reluctance.

The unit of magnetic flux is?

Description : The unit of magnetic flux is?

Last Answer : The unit of magnetic flux is weber.

The path of magnetic flux in a transformer should have?

Description : The path of magnetic flux in a transformer should have?

Last Answer : The path of magnetic flux in a transformer should have low reluctance.

Define permeance.

Description : Define permeance.

Last Answer : The reluctance is the opposition to the flow of magnetic flux. And the reciprocal of reluctance is known as permeance. The unit of reluctance is ampere per weber so the unit of permeance is ... . permeance is the property of magnetic circuit which allows the flow of magnetic flux through it.

Define reluctance and give its unit.

Description : Define reluctance and give its unit.

Last Answer : Reluctance is the resistance offered the material to the passage of magnetic flux through it and corresponds to resistance in the electric circuit it is denoted by (s) And it's unit is amper per weber (A/Wb)

Define the following terms and state their units: (i) Luminous intensity, (ii) Luminous flux

Description : Define the following terms and state their units: (i) Luminous intensity, (ii) Luminous flux

Last Answer : i) Luminous intensity: This is defined as the luminous flux emitted into a solid angle of space in a specific direction. Its unit is the candela.  OR  The luminous flux per unit solid angle ( ... energy radiated by the light source in all direction. The unit of luminous flux is lumen (lm) 

Compare variable reluctance and permanent magnet motors.

Description : Compare variable reluctance and permanent magnet motors.

Last Answer : Variable reluctance Motor  Permanent magnet motors   The rotor is not magnetised The rotor is magnetised  High torque to inertia ratio  Low torque to inertia ratio  ... rotor has salient pole construction The rotor has mostly smooth cylindrical type of construction. 

THE UNIT OF RELUCTANCE IS

Description : THE UNIT OF RELUCTANCE IS

Last Answer : The si unit of reluctance is Ampere-turn/weber

Reciprocal of reluctance is?

Description : Reciprocal of reluctance is?

Last Answer : Reciprocal of reluctance is permeance.

The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and

Description : The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is (A) 0.25 pu (B) 0.5 pu (C) 1.0 pu (D) 1.5 pu

Last Answer : The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is 0.5 pu

In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will?

Last Answer : In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will run as induction motor.

Reluctance motor

Description : Reluctance motor

Last Answer : Reluctance motor Reluctance is opposition to magnetic flux. Reluctance is analogous to electric resistance. Reluctance motor does not have any winding on rotor. Rotor consists of  ... for rotation of rotor is generated through magnetic reluctance so it called reluctance motor.

Define reluctance and permeance with respect to magnetic circuit.

Description : Define reluctance and permeance with respect to magnetic circuit.

Last Answer : Reluctance: The opposition offered by magnetic circuit to establish magnetic flux in it, is called as “Reluctance”.  Permeance: It is the reciprocal of reluctance and implies the magnetic core’s readiness with which magnetic flux is developed. 

Describe the concept of leakage flux, useful flux and fringing with neat diagram.

Description : Describe the concept of leakage flux, useful flux and fringing with neat diagram.

Last Answer : Leakage Flux

In lead acid battery the density of acid indicates the

Description : In lead acid battery the density of acid indicates the  (1) charge of the battery (2) level of acid (3) e.m.f of the battery (4) damage of the plates

Last Answer : In lead acid battery the density of acid indicates the charge of the battery

Define : i) MMF ii) Reluctance iii) Fringing iv) Leakage flux

Description : Define : i) MMF ii) Reluctance iii) Fringing iv) Leakage flux

Last Answer : i) MMF:  It is the force that drives magnetic flux through magnetic circuit. It is measured in amp-turns.  ii) Reluctance (s) :-  Reluctance is the property of the substance ... through the magnetic circuit, leaks through the air surrounding the core. This flux is called as leakage flux.

Define magnetic lines of force. Also draw and show magnetic lines of force of a bar type magnet.

Description : Define magnetic lines of force. Also draw and show magnetic lines of force of a bar type magnet.

Last Answer : Magnetic Lines of force- These are the imaginary lines (having no physical existence) introduced by Faraday for the pictorial representation of the distribution of a magnetic field.  OR  A line of ... that the tangent at any point gives direction of the resultant force at that point. 

Define magnetic lines of force. Show the magnetic lines of force for bar type magnet.

Description : Define magnetic lines of force. Show the magnetic lines of force for bar type magnet.

Last Answer : Magnetic linens of force is the imaginary lines for magnetic field of magnet around it. These magnetic lines of forces are introduced by Michael Faraday. The direction of lines of force is from N-pole to S-pole. The figure shows lines of force for bar type magnet.

In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation,

Description : In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as  (1) synchronous motor (2) synchronous generator (3) asynchronous motor (4) asynchronous generator

Last Answer : In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as synchronous generator 

It is possible to increase the field flux and, at the same time, increase the speed...

Description : It is possible to increase the field flux and, at the same time, increase the speed of a d.c. motor provided its .......... is held constant.

Last Answer : It is possible to increase the field flux and, at the same time, increase the speed of a d.c. motor provided its armature current is held constant.

Interpole flux should be sufficient to?

Last Answer : Interpole flux should be sufficient to neutralise both the armature reaction flux as well as commutating e.m.f. induced in the coil.

An energy signal has G(f) = 20. Its energy density spectrum is

Description :  An energy signal has G(f) = 20. Its energy density spectrum is A) 20 B) 100 C) 400 D) 800  

Last Answer : 400

Define magnetic permeability. State and explain the factors affecting permeability of magnetic materials

Description : Define magnetic permeability. State and explain the factors affecting permeability of magnetic materials

Last Answer : Permeability : The capability of the magnetic material to conduct the magnetic flux is known as permeability. Permeability and hysteresis loss are inversely related to each other. Factors ... impurities affect the geometric pattern of the crystals and are harmful to the magnetic property. 

Define magnetic field strength and state its unit.

Description : Define magnetic field strength and state its unit.

Last Answer : Magnetic field strength is the force experienced by a unit N-pole when placed at any point in a magnetic field is known as magnetic field strength or magnetizing force. Magnetising force or magnetic field ... unit of length is metre. So the unit of magnetic field strength is ampere turns per metre.

Important Terms in Magnetic Circuit

Description : Important Terms in Magnetic Circuit

Last Answer : Important Terms in Magnetic Circuit

State the material used for making (1) Magnetic Core (2) Fuse element

Description : State the material used for making (1) Magnetic Core (2) Fuse element  

Last Answer : The material used for making of:  (1) Magnetic Core : Iron, cobalt, Nickel, CRGO, HRGO , silicon steel  (2) Fuse Element: Tin- lead wire, Tinned copper wire 

What arc the errors occurring in measuring devices due to stray magnetic field and temp '? Explain how to compensate them.

Description : What arc the errors occurring in measuring devices due to stray magnetic field and temp '? Explain how to compensate them.

Last Answer : 1. Error due to stray magnetic fields-   Main magnetic field gets disturbed by external magnetic fields known as stray magnetic fields.  2. Compensation technique   To avoid this error, ... resistance alloy having a negligible resistance temp coefficient in the ratio of 1:10 for pressure coil 

Explain magnetic effect employed in measuring instrument.

Description : Explain magnetic effect employed in measuring instrument.

Last Answer : Magnetic Effect:  I) In PMMC meters:  ➢ When a current is passed through a conductor, magnetic field is produced round the conductor. Due to this field when current ... field it experiences a mechanical force.  Examples: Electrodynamometer type instruments, Induction type instrument. 

Derive an expression for energy stored in a magnetic field .

Description : Derive an expression for energy stored in a magnetic field . 

Last Answer : Expression for energy stored in a magnetic field: The energy is stored in magnetic field when current increases and return back when the current decreases. At instant t' seconds after closer of switch ... energy absorbed by the magnetic field when current increases from 0 to I amperes 

What is magnetic hysteresis? What is the cause of hysteresis?

Description : What is magnetic hysteresis? What is the cause of hysteresis?

Last Answer : Magnetic hysteresis: When a magnetic material is subjected to cycle of magnetization, it is found that flux density (B) in the material lags behind applied magnetizing force (H). This ... the movement of orientation, due to which the flux density lags behind the magnetic field intensity.

Classify magnetic materials and explain in brief.

Description : Classify magnetic materials and explain in brief.

Last Answer : .embed-container { position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden; max-width: 100%; } .embed-container iframe, .embed-container object, .embed-container embed { ... the absence of external magnetic field. Following are the ferromagnetic materials: Iron, Cobalt, Nickel.

Compare electric and magnetic circuit.

Description : Compare electric and magnetic circuit.

Last Answer : Comparison between Magnetic and Electric Circuits

The magnetic susceptibility of paramagnetic material is:

Description : The magnetic susceptibility of paramagnetic material is: A) Less than zero B) Less than one but positive C) Greater than one D) Equal to zero

Last Answer : The magnetic susceptibility of paramagnetic material is: Less than one but positive

Magnetic circuit breakers use _________

Description : Magnetic circuit breakers use _________ A) Permanent magnets B) Earth magnets C) Solenoid D) All the above

Last Answer : Magnetic circuit breakers use Solenoid 

Which of the following laws relates the magnetic field to the magnitude, direction, length, and proximity

Description : Which of the following laws relates the magnetic field to the magnitude, direction, length, and proximity of the electric current? A) Lenz’s law B) Faraday’s law C) Biot–Savart law D) None of these

Last Answer : Which of the following laws relates the magnetic field to the magnitude, direction, length, and proximity of the electric current? A) Lenz’s law B) Faraday’s law C) Biot–Savart law D) None of these

The magnetic permeability of a diamagnet is _________

Description : The magnetic permeability of a diamagnet is _________ A) More than that of vacuum B) Same as that of vacuum C) Less than that of vacuum D) 3.14 times that of vacuum

Last Answer : The magnetic permeability of a diamagnet is Less than that of vacuum 

The magnetic neutral plane shifts in a dc machine

Description : The magnetic neutral plane shifts in a dc machine (A) in the direction of motion of motor (B) in the direction of motion of generator (C) due to increase in the field flux (D) cause reduction of flash over between commutator segments

Last Answer : The magnetic neutral plane shifts in a dc machine in the direction of motion of generator

In a magnetic material hysteresis loss takes place primarily due to?

Description : In a magnetic material hysteresis loss takes place primarily due to?

Last Answer : In a magnetic material hysteresis loss takes place primarily due to it high retentivity.

A material for good magnetic memory should have?

Description : A material for good magnetic memory should have?

Last Answer : A material for good magnetic memory should have high retentivity.

Those magnetic materials are best suited for making armature and transformer cores which have...

Description : Those magnetic materials are best suited for making armature and transformer cores which have____permeability and_______hystersis loss.

Last Answer : Those magnetic materials are best suited for making armature and transformer cores which have high permeability and low hystersis loss.

Permeability in a magnetic circuit corresponds to______ in an electric circuit.

Description : Permeability in a magnetic circuit corresponds to______ in an electric circuit.

Last Answer : Permeability in a magnetic circuit corresponds to conductivity in an electric circuit.

An air gap is usually inserted in magnetic circuits to?

Description : An air gap is usually inserted in magnetic circuits to?

Last Answer : An air gap is usually inserted in magnetic circuits to prevent saturation.