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What do you mean by electromagnetic field?

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Description : What are the electromagnetic waves used in remote control?

Description : What are the dangers of electromagnetic waves?

Description : What is the speed of an electromagnetic wave in water?

Description : What is an example of an electromagnetic?

Description : What is the definition of electromagnetic force?

Description : How fast is an electromagnetic wave?

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

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 : What is the frequency range of VHF electromagnetic waves? A) 30-300 kHz B) 30-3000 kHz C) 30-300 MHz D) 30-3000 MHz

Answer : What is the frequency range of VHF electromagnetic waves? A) 30-300 kHz B) 30-3000 kHz C) 30-300 MHz D) 30-3000 MHz

Description : Define Faraday’s first law of electromagnetic induction. 

Answer : Faraday’s First Law: Whenever a changing magnetic flux links with a conductor, an emf is induced in that conductor.  OR  When a conductor cuts across magnetic field, an emf is induced in that conductor.

Description : State advantages & disadvantages of electromagnetic flow meter.

Answer : Advantage: Provides wide linear range. 2) Ability to measure reverses flow. 3) Gives rapid response to flow changes. 4) No obstruction is created to flow. 5) It can handle corrosive as ... and pipe networks with relatively short inside diameters. 3) It is useful for electrically conducting fluid.

Description : i) Explain electromagnetic spectrum with neat diagram. ii) Explain atmospheric noise with example. 

Answer : Explanation:-  The electromagnetic spectrum is the range of frequencies of electromagnetic radiation and their respective wavelengths  The electromagnetic spectrum covers ... spread over the complete frequency spectrum used for radio communication.  Example: Lightning 

Description : Justify electromagnetic wave is said to be transverse wave. 

Answer : Transverse electromagnetic wave:- The electromagnetic waves are oscillations which propagate through free space. In electromagnetic waves the direction of electric field, magnetic field & propagation are ... electric field vector with respect to the surface (i.e. looking at the horizon) 

Description : State Faraday's law of electromagnetic induction.

Answer : First Law: - Whenever change in the magnetic flux linked with a coil or conductor, an EMF is induced in it. OR Whenever a conductor cuts magnetic flux, an EMF is induced in conductor.  Second Law: ... of induced EMF is directly proportional to (equal to) the rate of change of flux linkages.

Answer : Magnetic field in a D.C. generator is produced by electromagnets.

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

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

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 : What is the direction of the induced electric field?

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

Description : What is the direction of the electric field?

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

Description : Why does the magnetic field flow from north to south?

Description : State advantages of rotating field type alternators. 

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.

Answer : magnetic field strength

Description : Briefly describe the electric field of a static charge.

Description :  Field intensity formula

Answer :  Field intensity formula

Description : Energy stored in electrostatic field of capacitance formula

Answer : Energy stored in electrostatic field of capacitance formula

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

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 . 

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 : Give the relation between magnetic field strength, magnetic flux density and permeability.

Description : Define magnetic field strength and state its unit.

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 : 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

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 

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

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

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

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.

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 : 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.

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.

Description : A field of force can exist only between?

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

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

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.

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

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.

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

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?

Answer : MOSFET uses the electric field of gate capacitance.

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

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

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

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?

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

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

Answer : It  can  only  if  they  have  equal  charges.

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

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

Description : Field control of DC motor

Answer : Field control of DC motor

Description : What do you mean by eco-friendly building materials? State any two properties of it.

Answer : Eco-friendly means earth-friendly or not harmful to the environment. This term most commonly refers to products that contribute to green living or practices that help conserve resources like water and ... It reduces air pollution, land pollution & water pollution. 7. It is locally available. 

Description : What do you mean by Gross National Product? a) The total value of goods and services produced in the country b) The total value of all transactions in the country c) Depreciation in the total ... d) The total value of goods and services produced in the country and net factor income from abroad

Answer : Answer- d

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