What is the SI unit for magnetic reluctance?
A) Ampere B) Ampere-turns per weber
C) Henry D) None of these
Description : Define the following terms: i) Magnetic flux density, ii) Reluctance, iii) Magneto-motive force, iv) Permeance.
Last 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 ... flux to set up through it and it is reciprocal of reluctance. Permeance = 1/ Reluctance. Unit: weber/ampere.
Description : THE UNIT OF RELUCTANCE IS
Last Answer : The si unit of reluctance is Ampere-turn/weber
Description : What is the SI unit of conductivity ?
Last Answer : The SI unit of conductivity Siemens/m.
Description : Which of the following is the SI unit for admittance? A) Ohm B) Henry C) Farad D) Siemens
Last Answer : Which of the following is the SI unit for admittance? A) Ohm B) Henry C) Farad D) Siemens
Description : Which of the following is an example of SI derived unit? A) Capacitance (Farad) B) Time (second) C) Luminous intensity (Candela) D) All the above
Last Answer : Which of the following is an example of SI derived unit? A) Capacitance (Farad) B) Time (second) C) Luminous intensity (Candela) D) All the above
Description : What are the SI derived units?
Last Answer : Electrical capacitance, electrical resistance, electrical inductance, force, energy, power, magnetic flux, electric charge, and electric potential difference and EMF. These are the nine SI derived units.
Description : The unit of power in S.I. units is
Last Answer : The unit of power in S.I. units is watt.
Description : The unit of work or energy in S.I. units is
Last Answer : The unit of work or energy in S.I. units is joule.
Description : The unit of force in S.I. units is
Last Answer : The unit of force in S.I. units is Newton.
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
Description : The unit of magnetic flux is?
Last Answer : The unit of magnetic flux is weber.
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)
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.
Description : Reciprocal of reluctance is?
Last Answer : Reciprocal of reluctance is permeance.
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
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.
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.
Description : Basic SI units
Last Answer : Basic SI units
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.
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
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.
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
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.
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
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.
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.
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.
Description : Compare electric and magnetic circuit.
Last Answer : Comparison between Magnetic and Electric Circuits
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.
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.
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
Description : Magnetic circuit breakers use _________ A) Permanent magnets B) Earth magnets C) Solenoid D) All the above
Last Answer : Magnetic circuit breakers use Solenoid
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
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
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
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.
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.
Description : A material for good magnetic memory should have?
Last Answer : A material for good magnetic memory should have high retentivity.
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.
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.
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.
Last Answer : Yes, Induction heating is used for both magnetic and non-magnetic materials.
Description : Define resistivity. State its unit.
Last Answer : Resistivity can be defined as the resistance of a conducting material per unit length with unit area of cross section. Its unit is ohm/meter
Description : What is the smallest unit of a compound with the same chemical characteristics?
Last Answer : The molecule is the smallest unit of a compound with the same chemical characteristics.
Description : Write the purpose of coal and ash handling unit. Also write different activities that arc carried out in this unit.
Last Answer : Purpose of coal and ash handling unit :- To transport coal from coal storage to power plant. A large quantity of ash about 10 to 30 % produced in furnace, the removal of ash from boiler furnace ... disposed off. Various methods of disposal of ash: Mechanical system. Pneumatic system.
Description : Define admittance and state its unit.
Last Answer : Admittance is defined as the ability of the circuit to carry (admit) alternating current through it. OR It is the reciprocal of impedance Z. i.e Admittance Y = 1/Z. Unit: Its unit is siemen (S) or mho (Ʊ).
Description : Which unit holds data permanently? (A) Input unit (B) Secondary storage unit (C) Output Unit (D) Primary Memory Unit
Last Answer : Which unit holds data permanently? (A) Input unit (B) Secondary storage unit (C) Output Unit (D) Primary Memory Unit
Description : The unit heat rate characteristic of a thermal power unit shows : (A) Heat input per kWh of output versus the megawatt output of unit (B) Heat input per kW of output versus the megawatt output ... hour output of unit (D) Heat input per kW of output versus the megawatt hour output of unit
Last Answer : The unit heat rate characteristic of a thermal power unit shows : Heat input per kWh of output versus the megawatt output of unit
Description : The unit of retentivity is?
Last Answer : The unit of retentivity is weber/sq. m.
Description : What is the unit of reactance?
Last Answer : Unit of reactance is Ohms ( Ω ) .Reactance is denoted by X .