What is meant by induced emf? By counter emf?

What is meant by induced emf? By counter emf?
by

1 Answer

Answer :

Induced emf is the emf which appears across a conductor when  there is relative motion between the conductor and a magnetic field;  counter emf is the emf induced in a conductor that opposes the  applied voltage.
by

Related questions

Why is no emf induced in a rotating coil when it passes through the neutral plane?

Description : Why is no emf induced in a rotating coil when it passes through the neutral plane?

Last Answer : No flux lines are cut.

What rule should you use to determine the direction of induced emf in a coil?

Description : What rule should you use to determine the direction of induced emf in a coil?

Last Answer : The left-hand rule for generators.

What motor characteristic is affected by counter emf?

Description : What motor characteristic is affected by counter emf?

Last Answer : Speed.

What causes counter emf in a dc motor

Description : What causes counter emf in a dc motor

Last Answer : Generator action.

The current in ampere through an inductor is i(10+20t) Here t is in second. The induced emf in the inductor 4V. Total flux linked with the inductor at

Description : The current in ampere through an inductor is i(10+20t) Here t is in second. The induced emf in the inductor 4V. Total flux linked with the inductor at

Last Answer : The current in ampere through an inductor is i(10+20t) Here t is in second. The induced emf in the inductor 4V. ... 10 Wb B. 20 Wb C. 30 Wb D. 40 Wb

The current in ampere through an inductor is i(10+20t) Here t is in second. The induced emf in the inductor 4V. The self inductance of the indicator i

Description : The current in ampere through an inductor is i(10+20t) Here t is in second. The induced emf in the inductor 4V. The self inductance of the indicator i

Last Answer : The current in ampere through an inductor is i(10+20t) Here t is in second. The induced emf in the inductor 4V. The ... B. `0.4` C. `0.1` D. `1.0`

Write down the equation for frequency of emf induced in an Altenator.

Description : Write down the equation for frequency of emf induced in an Altenator.

Last Answer : F = (PN)/120 Hz,Where P- Number of poles, N-Speed in rpm

On what factors does the induced emf in the coil depend?

Description : On what factors does the induced emf in the coil depend?

Last Answer : Induced e.m.f in a coil increases with increase in: a) the number of turns of the coil, b) the strength of the magnetic field c) the speed with which the magnet or the coil moves d) area of the coil

What is the equation used to find out frequency of number of cycles of induced emf?

Description : What is the equation used to find out frequency of number of cycles of induced emf?

Last Answer : f = NP/120

How we can find the direction of induced emf?

Description : How we can find the direction of induced emf? 

Last Answer : The direction of induced emf can be find out by the Fleming's right hand rule', and lenz's law' Fleming's right hand rule : Fleming's right hand rule states that, if ... that the action of magnetic field set up by induced current tends to opposes the root cause which produces it. 

Find the emf induced in a coil of 60 turns with a flux rate of 3 units. a) -60 b) -180 c) 60 d) 180

Description : Find the emf induced in a coil of 60 turns with a flux rate of 3 units. a) -60 b) -180 c) 60 d) 180

Last Answer : b) -180

The induced emf in a material opposes the flux producing it. This is a) Faraday law b) Ampere law c) Lenz law d) Curie law

Description : The induced emf in a material opposes the flux producing it. This is a) Faraday law b) Ampere law c) Lenz law d) Curie law

Last Answer : c) Lenz law

Find the induced EMF in an inductor of 2mH and the current rate is 2000 units. a) 4 b) -4 c) 1 d) -1

Description : Find the induced EMF in an inductor of 2mH and the current rate is 2000 units. a) 4 b) -4 c) 1 d) -1

Last Answer : b) -4

The direction of induced EMF can be found with the help of -

Description : The direction of induced EMF can be found with the help of -

Last Answer : Lenz’s Law

The induced emf in a coil depends upon: a. Strength of magnetic field b. Resistance of the coil c. area of the coil d. All of them

Description : The induced emf in a coil depends upon: a. Strength of magnetic field b. Resistance of the coil c. area of the coil d. All of them

Last Answer : d. All of them

Which of the following will produce an induced emf: a. Changing area of coil b. Changing magnetic flux c. changing orientation of coil d. all of them

Description : Which of the following will produce an induced emf: a. Changing area of coil b. Changing magnetic flux c. changing orientation of coil d. all of them

Last Answer : c. changing orientation of coil

The phenomena of induced emf was observed by Faraday and Henry in: a. 1931 b. 1831 c. 1535 d. 1940

Description : The phenomena of induced emf was observed by Faraday and Henry in: a. 1931 b. 1831 c. 1535 d. 1940

Last Answer : a. 1931

In the plane of AC generator coil is parallel to the field, then emf induced in coil is: a. maximum b. minimum c. zero d. intermediate

Description : In the plane of AC generator coil is parallel to the field, then emf induced in coil is: a. maximum b. minimum c. zero d. intermediate

Last Answer : b. minimum

In the plane of the A.C generator coil is perpendicular to the field, then induced emf in the coil is: a. Maximum b. minimum c. zero d. intermediate value

Description : In the plane of the A.C generator coil is perpendicular to the field, then induced emf in the coil is: a. Maximum b. minimum c. zero d. intermediate value

Last Answer : b. minimum

A wire loop is moved parallel to a uniform magnetic field. The induced emf in the loop: a. depends on the shape b. depends on area c. depends on nature of loop d. zero

Description : A wire loop is moved parallel to a uniform magnetic field. The induced emf in the loop: a. depends on the shape b. depends on area c. depends on nature of loop d. zero

Last Answer : d. zero

The current flowing in a coil due to induced emf depends upon: a. shape of coil b. resistance of coil c. area of coil d. magnetic flux

Description : The current flowing in a coil due to induced emf depends upon: a. shape of coil b. resistance of coil c. area of coil d. magnetic flux

Last Answer : a. shape of coil

The induced emf is produced in a circuit due to: a. Initial magnetic flux b. final magnetic flux c. Change of magnetic flux d. constant magnetic flux

Description : The induced emf is produced in a circuit due to: a. Initial magnetic flux b. final magnetic flux c. Change of magnetic flux d. constant magnetic flux

Last Answer : d. constant magnetic flux

28.In a two winding transformer, the emf /turn in secondary winding is always......the induced emf power turn in primary A. equal to k times B. equal to 1/k times C. equal D. greater than

Description : 28.In a two winding transformer, the emf /turn in secondary winding is always......the induced emf power turn in primary A. equal to k times B. equal to 1/k times C. equal D. greater than

Last Answer : C. equal

6 In a two winding transformer, the primary and secondary induced emf E1 & E2 are always A. equal in magnitude B. anti phase with each other C. in phase with each other D. determined by load on transformer secondary

Description : 6 In a two winding transformer, the primary and secondary induced emf E1 & E2 are always A. equal in magnitude B. anti phase with each other C. in phase with each other D. determined by load on transformer secondary

Last Answer : C. In phase with each other

Slip of the induction machine is 0.02 and the stator supply frequency is 50 Hz. What will be the frequency of the rotor induced emf? (A) 10 Hz. (B) 50 Hz. (C) 1 Hz. (D) 2500 Hz.

Description : Slip of the induction machine is 0.02 and the stator supply frequency is 50 Hz. What will be the frequency of the rotor induced emf? (A) 10 Hz. (B) 50 Hz. (C) 1 Hz. (D) 2500 Hz.

Last Answer : Ans: C Given : s = 0.02 ; f = 50 Hz Therefore, frequency of rotor induced emf = s f = 0.02 x 50 = 1.0 Hz

The emf induced in the primary of a transformer (A) is in phase with the flux. (B) lags behind the flux by 90 degree. (C) leads the flux by 90 degree. (D) is in phase opposition to that of flux.

Description : The emf induced in the primary of a transformer (A) is in phase with the flux. (B) lags behind the flux by 90 degree. (C) leads the flux by 90 degree. (D) is in phase opposition to that of flux.

Last Answer : (C) leads the flux by 90 degree.

Explain statically induced EMF and Dynamically induced EMF with neat diagrams.

Description : Explain statically induced EMF and Dynamically induced EMF with neat diagrams.

Last Answer : Statically Induced EMF:- When changing magnetic field links with a stationary coil an emf is induced. This emf is called statically induced emf. Statically induced EMF is of two types: Self-induced ... cuts the field and an emf is induced. This emf is called dynamically induced emf.    

List the types of induced emf.

Description : List the types of induced emf.

Last Answer : The types of induced emf are : i) Statically induced emf , ii) Dynamically induced emf

Define self induced Emf. Write equation of self induced Emf.

Description : Define self induced Emf. Write equation of self induced Emf. 

Last Answer : Definition: Self-induced emf is the e.m.f induced in the coil due to the change of flux produced by linking it with its own turns. Or Self induced emf is that which is induced in a coil, due to the change in its own current or flux. Self induced emf equation. E = - N (dΦ/dt) volts

Define self and mutual induced emf.

Description : Define self and mutual induced emf.

Last Answer : Self-induced emf: Self-induced emf is the e.m.f induced in the coil due to the change of flux produced by linking it with its own turns. Mutual induced emf: The emf induced in a coil due to the change of flux produced by another neighbouring coil linking to it, is called Mutually Induced emf.   

The greatest induced EMF will occur in a straight wire moving at constant speed through a uniform magnetic field when the angle between the direction of the wire's motion and the direction of the magnetic field is w) 0 degrees x) 30 degrees y) 60 degrees z) 90 degrees

Description : The greatest induced EMF will occur in a straight wire moving at constant speed through a uniform magnetic field when the angle between the direction of the wire's motion and the direction of the magnetic field is w) 0 degrees x) 30 degrees y) 60 degrees z) 90 degrees

Last Answer : ANSWER: Z -- 90 DEGREES

Explain dynamic and static induced emf with neat diagram.

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

Last 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).

Self induced emf and Mutually induced emf

Description : Self induced emf and Mutually induced emf

Last 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. 

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

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

Last 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

Define: 1) statically induced EMF 2) dynamically induced EMF

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

Last 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.

List the two types of induced EMF.

Description : List the two types of induced EMF.

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

The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors

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

Last 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

When a conductor cuts magnetic flux, an emf is induced in the conductor. This is known as...

Description : When a conductor cuts magnetic flux, an emf is induced in the conductor. This is known as  (a) Joule's law (b) Faraday's law (c) Coulomb's law (d) Ampere’s law

Last Answer : When a conductor cuts magnetic flux, an emf is induced in the conductor. This is known as Faraday's law. There are two Faraday's law of electromagnetic induction. 1. Changing flux produces emf ... 2. Magnitude of induced e.m.f. is directly proportional to rate of change of flux linkage.

Which of the following statements describes what will occur if the motor shown in the illustration is required to carry 150% of full load? EL-0056 A. The primary counter emf will be increased. B. The stator current will increase. C. The slip will decrease. D. The slip value, stator current curve, and torque curve will all coincide.

Description : Which of the following statements describes what will occur if the motor shown in the illustration is required to carry 150% of full load? EL-0056 A. The primary counter emf will be increased. B. ... slip will decrease. D. The slip value, stator current curve, and torque curve will all coincide.

Last Answer : Answer: B

An increase in the amount of current flow through the armature of a shunt motor is the final result of a/an _____________. A. increase in the load on the motor B. decrease in the load on the motor C. increase in counter EMF D. decrease in armature torque

Description : An increase in the amount of current flow through the armature of a shunt motor is the final result of a/an _____________. A. increase in the load on the motor B. decrease in the load on the motor C. increase in counter EMF D. decrease in armature torque

Last Answer : Answer: A

In the illustration, the diode between terminals 16 and 17 is to _________. EL-0046 A. insure that the voltage across the governor coil (EG-3P) never exceeds .6 VDC B. compensate for the temperature difference of the governor oil heating up C. protect the electronic governor from counter EMF D. act as a filter to prevent hunting

Description : In the illustration, the diode between terminals 16 and 17 is to _________. EL-0046 A. insure that the voltage across the governor coil (EG-3P) never exceeds .6 VDC B. compensate for the ... heating up C. protect the electronic governor from counter EMF D. act as a filter to prevent hunting

Last Answer : Answer: C

The counter EMF of a DC motor is maximum when the _________. A. motor is at rated speed B. armature is not turning C. motor is almost up to rated speed D. armature has just begun to turn

Description : The counter EMF of a DC motor is maximum when the _________. A. motor is at rated speed B. armature is not turning C. motor is almost up to rated speed D. armature has just begun to turn

Last Answer : Answer: A

The counter EMF produced in the windings of a DC motor is 'zero' when the ____________. A. armature has just begun to turn B. armature is not turning C. motor is almost up to rated speed D. motor is at rated speed

Description : The counter EMF produced in the windings of a DC motor is 'zero' when the ____________. A. armature has just begun to turn B. armature is not turning C. motor is almost up to rated speed D. motor is at rated speed

Last Answer : Answer: B

Which of the following types of DC motors has its field connected in parallel with its armature? A. Counter EMF B. Shunt C. Salient pole D. Series

Description : Which of the following types of DC motors has its field connected in parallel with its armature? A. Counter EMF B. Shunt C. Salient pole D. Series

Last Answer : Answer: B

The ratio of the effective value of the counter EMF in volts, to the effective value of the current in amperes is called _____________. A. impedance factor B. capacitive reactance C. inductive reactance D. root mean square

Description : The ratio of the effective value of the counter EMF in volts, to the effective value of the current in amperes is called _____________. A. impedance factor B. capacitive reactance C. inductive reactance D. root mean square

Last Answer : Answer: C

What is the name of the emf generated in the primary that opposes the flow of current in the primary?

Description : What is the name of the emf generated in the primary that opposes the flow of current in the primary?

Last Answer : . Self-induced or counter emf

What term describes voltage or emf?

Description : What term describes voltage or emf?

Last Answer : Difference of potential.

An emf is generated in a conductor when the conductor is cut by what type of field?

Description : An emf is generated in a conductor when the conductor is cut by what type of field?

Last Answer : Magnetic field.

The introduction of interpoles in between the main pole improves the performance of d.c. machines, because (A) The interpole produces additional flux to augment the developed torque. (B) The flux waveform is improved with reduction in harmonics. (C) The inequality of air flux on the top and bottom halves of armature is removed. (D) A counter e.m.f. is induced in the coil undergoing commutation.

Description : The introduction of interpoles in between the main pole improves the performance of d.c. machines, because (A) The interpole produces additional flux to augment the developed torque. (B) The flux waveform is ... armature is removed. (D) A counter e.m.f. is induced in the coil undergoing commutation.

Last Answer : Ans: D Counter e.m.f is produced, it neutralizes the reactive emf.

What is the amplitude and voltage induced into the rotor when the CX is turned 90º while the CT remains on electrical zero?

Description : What is the amplitude and voltage induced into the rotor when the CX is turned 90º while the CT remains on electrical zero?

Last Answer : The voltage is maximum and in phase with the ac excitation voltage to the CX.