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What is back EMF in inductor?

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Description : What is the back EMF in Transformers?

Description : What is back emf? 

Answer : Back EMF: When a current carrying conductor is placed in a magnetic field it experiences a force; when it moves due to the force it (conductor) cuts the magnetic field due to which an emf is ... (hence the applied armature voltage) is opposed by the induced emf which is therefore called as Back emf.

Description : What is back EMF of synchronous motor?

Description : What is the back EMF of a dc motor?

Description : What is the back EMF of the motor?

Description : What is the back EMF?

Answer : When the armature of a d.c. motor rotates under the influence of the driving torque, the armature conductors move through the magnetic field and hence e.m.f. is induced in them as in a generator. The ... that energy conversion in a d.c. motor is only possible due to the production of back emf.

Description : Do AC induction motors have back EMF?

Description : The back emf of synchronous motor depends on?

Answer : The back emf of synchronous motor depends on load angle.

Answer : The armature may burn if the back e.m.f. of a D.C. motor vanishes suddenly.

Answer : In case of D.C. shunt motors the speed is dependent on back e.m.f. only because flux is practically constant in D:C. shunt motors.

Answer : The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 0.5.

Description : What is the difference between a coil and an inductor?

Answer : Inductor is covering with insulating material is called coil.so they differentiate between coil and inductor.

Description : An inductor of Q factor 10 is connected in series with a capacitor having a Q factor of 100. The overall Q factor of the circuit is :  (A) 100/11 (B) 11/100 (C) 110 (D) 1000

Answer : An inductor of Q factor 10 is connected in series with a capacitor having a Q factor of 100. The overall Q factor of the circuit is : 100/11

Description : Why inductor current lags inductor voltage ?

Answer : Inductor is a wire wounding structure having a core material it induces emf which is opposite to the voltage supply and proportional to rate of change of current so current lags the voltage in inductor

Description : What are the types of power losses in inductor?

Answer : Copper losses, Eddy current loss, and hysteresis loss are the types of power losses in inductor.

Description : An inductor is connected in series with SCR to protect it from A) Excessive high voltage B) Excessive high dv/dt C) Excessive high di/dt D) Excessive large forward current 

Answer : An inductor is connected in series with SCR to protect it from Excessive high di/dt

Description : State the applications and specification of (i) Resistor (ii) Capacitor (iii)Inductor

Answer : Application of resistor: 1.Resistors are used in high frequency instrument. 2.Resistor is used in power control circuit. 3.It is used in DC power supplies. 4.Resistors are used ... DC Current  3.Electromagnetic Interference (EMI)  4.Magnetic Saturation Flux Density  5.Curie Temperature 

Description : Explain design constraint of filter inductor design.

Description : Explain the characteristics of inductor to be considered while designing it. What is the effect of over current and increase in temperature on inductor.

Description : Explain the iterative inductor design procedure. Show the design procedure flowchart.

Description : What is Phase sequence? Draw waveforms of 3 phase emf.

Answer : Phase sequence: It is the order in which the three phases reach their peak or maximum values. It is shown in below fig. the phase sequence is A-B-C (or R-Y-B). In the following waveforms, it is ... 120º, B- phase voltage attains its positive maximum value. So the phase sequence is R-Y-B. 

Description : Self induced emf and Mutually induced emf

Answer : (i) Self-induced e.m.f.: The e.m.f. induced in a coil due to the change of its own flux linked with it, is called self-induced e.m.f.  (ii) Mutually induced e.m.f.: The e.m.f. induced in a coil due to the changing current in the neighbouring coil, is called mutually induced e.m.f. 

Description : Compare statically induced emf with dynamically induced emf on any four points.

Answer : Statically induced emf Dynamically induced emf Emf is induced without any relative motion between conductor and magnetic field. Emf is induced due to relative motion between conductor ... induced in transformer windings e.g emf induced in Generator, Alternator armature windings

Description : Explain the term self induced EMF with a neat diagram.

Description : Define: 1) statically induced EMF 2) dynamically induced EMF Write the names of equipments in which these two types of EMF get induced

Answer : Concept of statically induced emf: The emf induced in coil or conductors without any relative motion between it and magnetic field is called statically induced emf. When conductor is stationary and flux ... it. This emf is dynamically induced emf. e.g. Emf induced in generators, alternator.

Description : List the two types of induced EMF.

Answer : There are two types of EMF one is statically induced EMF and second is dynamically induced EMF.

Description : What is the EMF equation of the transformer?

Answer : E1 =2(3.142)fN1 (flux)1E2 =2(3.142)fN2(flux)2

Description : Symptoms of Back Pain Causes And Tips

Answer : Symptoms of Back Pain Causes And Tips Back pain is the most common complaint heard among the adults these days. It has been estimated that people do suffer from back pain at least once in their ... night sleep that will recover from all the bodily disorders and you wake up fresh the next morning.

Description : The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors rotating at 600 rpm and with 1 Wb flux per pole is  (1) 1000V (2) 100V (3) 600V (4) 10,000V

Answer : The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors rotating at 600 rpm and with 1 Wb flux per pole is 1000V

Description : Explain dynamic and static induced emf with neat diagram.

Answer : Dynamically Induced EMF:-  In this case, either coil moves or magnet moves, so that there is relative motion between coil & magnetic field. Thus magnetic field is cut by coil & emf is induced in it. The emf ... The expression for induced EMF is e= -L(di/dt) or = -N(dϕ/dt).

Description : The fractional-pitch used for eliminating 7th harmonic from the emf wave of an alternator is (A) 2/3 (B) 5/6 (C) 7/8 (D) 6/7

Answer : The fractional-pitch used for eliminating 7th harmonic from the emf wave of an alternator is 6/7

Description : A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will?

Answer : A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will not start at all.

Description : The counter e.m.f. of a d.c. motor?

Answer : The counter e.m.f. of a d.c. motor helps in energy conversion.

Answer : E.m.f. of a Weston cell is accurately measured by electrostatic voltmeter.

Answer : It is required to measure the true open circuit e.m.f. of a battery. The best device is D.C. potentiometer.

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.

Answer : When the armature of a D.C. motor rotates, e.m.f. induced is back e.m.f.

Answer : Back emf: When the armature of DC motor rotates under the fixed magnetic field and cuts it, by Faraday's law an emf is induced in them. The induced emf acts in opposite direction to the ... the flow of armature current i.e. it automatically changes the armature current to meet load requirements. 

Description : In an isolated output dc-to-dc fly back converter, the high frequency transformer used works as an inductor (a) during turn -on period of the switching device (b) during turn off period of the switching device (c) during both (d) none of these

Description : If the back emf of a dc motor is doubled and its speed is also doubled, the torque developed in the machine will  (1) get doubled (2) become 4 times (3) get halved (4) remain unaltered

Description : Explain concept of back emf in DC machine. State how it governs armature current. 

Answer : Back emf: When the armature of DC machine rotates under the influence of driving torque, the armature conductors move in the magnetic field and cut it and hence emf is induced in them. The ... flow of armature current i.e. it automatically changes the armature current to meet load requirements.

Description : A 200 V dc motor takes a field current of 2 A to generate a back emf of 180 V. If the field winding resistance is 80 Ω, the resistance of the shunt field regulator is (A) 10 Ω (B) 20 Ω (C) 100 Ω (D) 180 Ω

Description : A single-phase half-controlled rectifier is driving a separately excited dc motor. The dc motor has a back emf constant of 0.5 V/rpm. The armature current is 5 A without any ripple. The armature resistance is 2 Ohm. The ... of the motor will be  (A) 339 rpm (B) 359 rpm (C) 366 rpm (D) 386 rpm

Answer : 359

Description : What is the reactance of a 3H inductor when the frequency is 120 Hz? A. 2260 ohm B. 2060 ohm C. 360 ohm D. 0  

Answer : 2260 ohm is the reactance of a 3H inductor when the frequency is 120 Hz.

Description : What is application of inductor?

Answer : Inductors are use in analog circuits.

Description : What is called the EIectro-Motive Force (EMF) of a voltage source? (1) Terminal voltage when load is applied (2) Internal voltage when no load is applied (3) Product of internal resistance and load current (4) Electric pressure provided to the load

Answer : What is called the EIectro-Motive Force (EMF) of a voltage source? (1) Terminal voltage when load is applied (2) Internal voltage when no load is applied (3) Product of internal resistance and load current (4) Electric pressure provided to the load

Description : (b) Consider the circuit shown under the DC-steady-state condition. (i) Re-draw the circuit by replacing the capacitor and inductor with open and short-circuit. (ii) ... and the voltage, VC. (iii) Calculate the energy stored in the inductor and capacitor, respectively. 

Description : In a series RLC circuit, the rms value of voltage across the resistor is 30 V, across the inductor is 60 V and across the capacitor is 20 V. The rms supply voltage would be (A) 110 V (B) 10 V (C) 220 V (D) 50 V

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