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

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.

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.

## Related questions

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

Last Answer : If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens this will make armature to take heavy current, possibly burning it.

Description : Flux density formula

Last Answer : Flux density formula

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)

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

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 : 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

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 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 : The unit of magnetic flux is?

Last Answer : The unit of magnetic flux is weber.

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.

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.

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.

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.

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.

Description : An electric motor in which both stator field and rotor rotates with same speed is called?

Last Answer : An electric motor in which both stator field and rotor rotates with same speed is called synchronous motor.

Description : How to Kick a Football Field Goal

Last Answer : How to Kick a Football Field Goal There are only a few seconds left in the game, and one field goal attempt is all that stands between you and gridiron glory, or a place in the Hall of Shame. ... right kick for the right play, and get that game-winning field goal just right between the goal posts.

Description : How to Plow a Field

Last Answer : How to Plow a Field Civilization began when human beings started to turn over the soil to plant food. Plowing may have come a long way since the first human beings used their hands and ... budget. With these tools, you can plow fields and help contribute to the advancement of human civilization.

Description : How to Field Dress a Deer ?

Last Answer : How to Field Dress a Deer If you enjoy hunting deer, there's one important task you need to do before you can haul your prized catch back home: you'll need to field dress it. Field dressing ... you go hunting. Just follow these steps and you'll bring your prized catch home without any trouble.

Description : State advantages of rotating field type alternators.

Last Answer : Advantages of Rotating Field Type Alternator: 1) For high-voltage alternator, large space is required to accommodate conductors with insulation, as high voltage is induced in them. If field poles are placed ... is kept rotating. 8) Rotating field is comparatively light and can run with high speed.

Description : A magnetic circuit has effective iron length of 100 cm and it is wound with 800 turns of wire carries 1 A. Find the magnetic field strength.

Last Answer : magnetic field strength

Description :  Field intensity formula

Last Answer :  Field intensity formula

Description : Energy stored in electrostatic field of capacitance formula

Last Answer : Energy stored in electrostatic field of capacitance formula

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 : Define junction field effect transistor (JFET) and give an example.

Last Answer : Junction Field-Effect Transistor: It is a semiconductor device having three terminals, namely Gate, Drain and Source, in which the current flow is controlled by an electric field set up by an external voltage applied ... : i) n-channel JFET and ii) p-channel JFET Examples of JFET: BFW 10, BFW 11

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 : 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 : The ability of materials to become polarized under an applied electric field is called _______ A) Ferroelectricity B) Paraelectricity C) Polectricity D) None of these

Last Answer : The ability of materials to become polarized under an applied electric field is called Paraelectricity

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 electric field inside a hollow conducting sphere ________ A) Depends on the diameter of the sphere  B) Varies according to the direction of earth’s magnetic poles C) Is zero  D) None of these

Last Answer : The electric field inside a hollow conducting sphere Is zero

Description : Which of the following statements is not characteristic of a static magnetic field? (A) It is solenoidal. (B) It is conservative. (C) It has no sinks or sources. (D) Flux lines are always closed.

Last Answer : Which of the following statements is not characteristic of a static magnetic field? (A) It is solenoidal. (B) It is conservative. (C) It has no sinks or sources. (D) Flux lines are always closed.

Description : A field of force can exist only between?

Last Answer : A field of force can exist only between two ions.

Last Answer : To avoid the effect of stray magnetic field in A.C. bridges we can use magnetic screening.

Description : A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave?

Last Answer : A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave will be of 5 Hz.

Last Answer : Flashing the field of D.C. generator means creating residual magnetism by a D.C. source.

Last Answer : If the field of a D.C. shunt motor gets opened while motor is running the motor will attain dangerously high speed.

Last Answer : In a shaded pole single-phase motor, the revolving field is produced by the use of shading coils.

Last Answer : If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will stop.

Description : MOSFET uses the electric field of?

Last Answer : MOSFET uses the electric field of gate capacitance.

Description : If the field of synchronous motor is under excited, power factor will be?

Last Answer : If the field of synchronous motor is under excited, power factor will be lagging.

Description : Is electric potential zero when electric field is zero?

Last Answer : Yes  .If  electric  field  is  zero  then  electric  potential  is  zero  ,  not  even  one.

Description : What is the direction of the induced electric field?

Last Answer : It  is  in  opposite  direction   to  the  one  that   produced  it.

Description : Can the electric field between two positive charges be zero?

Last Answer : It  can  only  if  they  have  equal  charges.

Description : What is the direction of the electric field?

Last Answer : Electric   field    is  at   right angle   widh  flow  of  current  (right  hand   rule).

Description : How can a magnetic field be used to generate an electric current?

Last Answer : Magnetic  field  can  be  used  to  generate  electric  current  on  a  condition  that  it  is  on  a  rate  of  changing  magnetic  flux.  (Faraday's  law)

Description : From which material field coils of DC generator are made of?

Last Answer : Field coils of DC generator are usually made of copper.

Description : Field control of DC motor

Last Answer : Field control of DC motor

Description :  A DC Motor develops a torque of 150 N-m. A 10 percent reduction in the field flux causes a 50 percent increase in armature current. The new value of torque is: A) 102.5 N-m B) 202.5 N-m C) 172.5 N-m D) 232.5 N-m

Last Answer : T1=KIf,T2=K1.5I*0.9f T1=150Nm.  T2=T1*1.5*0.9=150*1.35=202.5Nm